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News from Rohde & Schwarz

MultimediaRohde & Schwarz right there from the start

Radio test and measurementInnovation in mobile phone testing

ATC radiocommunicationsNow with RCMS and 8.33-kHz channel spacing

152

2 News from Rohde & Schwarz Number 152 (1996/III )

Number 152 1996/III Volume 36

Digital broadcasting and multimedia communi-cation are the topics of our final article (page 57)which breaches the gap between the world of ana-log sound and TV broadcasting and that of digitalaudio and video broadcasting with its interactivecommunication facilities. The photo on the cover isto give an impression of this multimedia world. Formore information about digital TV see our articleson pages 17 and 20.

Michael Vohrer Digital Radio Tester CTS55All-in-one service tester for GSM, PCN and PCS mobile telephones. . . . . . . . . . . .4

Josef Wolf Spectrum Analyzer FSEM/FSEKFast spectrum analysis now through to 40 GHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Jon Pedersen Calibration System TS9099Automatic test equipment calibration to ISO 9000 . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Thomas Kneidel System Processor MERLIN GR2000Powerful processor stands toughest conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Hans-Günther Klarl; Series 200 and 400U radio equipmentMartin Kessler Innovations in ATC radiocommunications: RCMS and 8.33-kHz channel spacing...14

Christoph Balz; Ernst Polz; TV Test Receiver Family EFAWalter Fischer Top fit for digital television. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Michael Fischbacher; MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMDHarald Weigold Test equipment for digital TV in line with MPEG2 . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Rainer Steen; 100/200-W Solid-State DAB Transmitter NL5010/5020Johannes Steffens Terrestrial broadcasting of digital audio in L band . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Walter Deschler; TV Transmitter Test System TS6140Gerhard Strauss Guarantee of high signal quality in TV transmitter networks . . . . . . . . . . . . . . . . . .27

Franz Demmel; VHF-UHF Direction Finder DDF190Raimund Wille Digital direction finding from 20 to 3000 MHz to ITU guidelines . . . . . . . . . . . .30

Wilhelm Kraemer EMC measurements up to 40 GHz withMicrowave Signal Generator SMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Tilman Betz Measurements on hearing aids with Audio Analyzers UPD and UPL. . . . . . . . . .36

Thomas Maucksch Quality testing of mobile phones using multitone audio analysis of Digital Radiocommunication Tester CMD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Joachim Stegmaier Tailor-made applications in industrial automation withfactory user port for Controller PSM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Günter Wicker; Fast adaptive data transmission on shortwaveGerhard Greubel at up to 5400 bit/s via HF Modem GM2100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

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Application notes

Peter Hatzold Digital modulation and mobile radio (III). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

Refresher topic

3News from Rohde & Schwarz Number 152 (1996/III )

Published by ROHDE & SCHWARZ GmbH & Co. KG Mühldorfstraße 15 D -81671 MunichTelephone (0 89) 41 29-0 · international *(4989) 41 29-0 · Telex 523703 (rs d) · Editors: H. Wegener and G. Sönnichsen (German); G. Koranyi, I. Davidson, C. B. Newberry (English) · Photos: S. Huber ·Circulation 100 000 three times a year · ISSN 0028-9108 · Supply free of charge · State companyor position · Printed in the Federal Republic of Germany by peschke druck, Munich · Reproduction ofextracts permitted if source is stated and copy sent to R & S Munich

Imprint

Software

Dr. Hans Waibel; PropWiz – Windows program for shortwave radio linkPeter Maurer prediction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Panorama

Werner Mittermaier Digital Radiocommunication Tester CMD55 with new measurement functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Andreas Schneider ACCESSNET® – a solution for communications in Russia. . . . . . . . . . . . . . . . . . . . .49

Klaus Wunderlich; Rohde & Schwarz test equipment in EMC test center ofPeter Busch safety standards authority of Hesse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

Jacques Stellamans SNCB uses R&S test system for planning and quality assurancein Belgian railway communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Regular features

Reference: EMC system solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Marcus Gloger; Test hint: Peter Riedel Optimizing wireless local loop systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Klaus Danzeisen Patent: Frequency-selective measurement and displayof frequency-dependent test parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Information in print . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Newsgrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

In memoriam Dr. Rohde . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Press comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Paul Dambacher Final article: Digital broadcastingand multimedia communication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57

The future of sound broadcasting is digital – andRohde & Schwarz is the perfect partner. The mostrecent member in our family of DAB transmitters is100/200-W Solid-State Transmitter NL5010/5020for the L band (page 24).


Digital Radio Tester CTS55 (FIG 1) is asynthesis of fast function testing andclassic measurement technology forGSM 900, DCS 1800 (PCN) and DCS1900 (PCS) mobile radio systems. It is

CTS55’s quick function test can becalled at the press of a button andproduces all the important features of a mobile telephone on different RFchannels. As well as a go or nogo

an optimum combination of the GSM/DCS features of Go/NoGo Testers CTD[1] and the in-depth testing of DigitalRadiocommunication Tester CMD [2; 3]for joint coverage of all aspects of servicing from simple function teststhrough to repairs. Its brilliant, high-resolution colour display makes usingCTS55 a joy and allows it to show offits strong points, in particular the resultgraphics.

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Digital Radio Tester CTS55

All-in-one service tester for GSM,PCN and PCS mobile telephonesDigital Radio Tester CTS55 from Rohde & Schwarz is a cost-effective, compact tester for all servicing, maintenance and repair work on GSM, PCN and PCS mobile radiotelephones in a single unit. It therefore bridges the gap between purego/nogo tests and sophisticated GSM measurement technology.

FIG 1 Digital Radio Tester CTS55 provides fastfunction testing combined with in-depth mobilephone tests to GSM, PCN and PCS.

Photo 42 434

FIG 2 CTS55 autotest automatically checks all mobile phone characteristics on various RFchannels and displays result as go/nogo or nu-merically with out-of-tolerance warnings.


display for the particular parameterand an overall evaluation, test resultscan also be shown in very simple nu-merical form with out-of-range displaystoo (FIG 2). A digital signal processorallows you to determine power ramp-ing, phase and frequency error and bit error rate in a form like that used by Digital Radiocommunication TesterCMD. Not only can these functions becalled during automatic test sequences,in conjunction with other test facilitiesthey are also available in the classicmanual mode. This second mode ofoperation enables CTS55 to fulfil all therequirements of a high-flexibility repairtester. In addition to the wide range ofdigital result displays in a highly prac-tical format (FIG 3), graphics for testparameters such as power ramping orphase error can be selected with asingle keystroke. For in-depth analysisthere are zoom functions which simplifythe interpretation of anomalies and somake servicing easier.

CTS55 has the following test andmeasurement facilities for fast testingand in-depth analysis of mobilephones:

• synchronization of mobile phoneswith base stations (simulated byCTS55),

• registration (location update),• incoming and outgoing call setup,• incoming and outgoing call clear-

down,• control and measurement of trans-

mitting power,• handover (channel change),• measurement of peak power,• sensitivity measurement (RxQual,

RxLev),• function test on dialling pad by

displaying the called number,• display of IMSI (international mobile

subscriber identity) and IMEI (inter-national mobile equipment identity),

• echo test,• bit error rate and frame error rate

measurements,• phase error measurement,• frequency error measurement,• power ramping measurement.

During the fast function test or go/nogotest CTS55 measures all the parametersof the mobile phone on any selectableRF channel and clearly displays thefunction in the form of individualevaluations and of an overall eval-

uation. If required, a test report can beoutput on a printer to show whetherrepairs are necessary or only asbackup documentation. When theclassic manual mode is used, allmeasurements can be called up with acontinuous result display. This makesalignments and troubleshooting easy ifrepairs have to be made. In particular,the graphic displays showing phase er-ror, frequency error (FIG 4) and powerramp (FIG 5) give an exhaustive de-scription of the transmitter and make iteasy to determine the causes of faults.The simultaneous display of the variousbit error rates and frame error rateswith a user-selectable measurementinterval gives you a relatively deepunderstanding of receiver character-istics (FIG 6).

Operation of Digital Radio TesterCTS55 is especially simple, with just sixsoftkeys and easy-to-understand screenprompts. A sophisticated menu struc-ture navigates almost automaticallythrough the measurement, and the multilingual user interface (English, Ger-man, French, Italian, Dutch, Spanish)prevents misinterpretations and incor-rect operation. Direct access softkeysare used to control the tester. This alsoincludes calling tests and selecting parameters; an ASCII keyboard can also be connected. If an automatic testsequence is being run, it is possible tochange over to graphic mode to carryout additional detailed analysis if anout-of-tolerance condition is encoun-tered for example.

Digital Radio Tester CTS55 is designedas a mini base station with indepen-dent transmit and receive channels andrealtime signalling for the broadcastcontrol channel (BCCH) and trafficchannel (TCH). Several processorsgenerate and analyze test signals orare used to return the words spokeninto the microphone to the mobile tele-phone receiver with a defined delay.

Digital Radio Tester CTS55 measuresall parameters that could influence cor-rect phone operation. Besides power

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FIG 4 Phase/frequency curve and numericaldisplay of current, average and maximum valueprovide information about modulation charac-teristics of mobile phone.

FIG 3 In manual mode CTS55 simultaneouslyindicates all relevant test values and parameters onits display.


level it determines phase and frequencyerror and power ramping as well as thevarious bit error rates and frame errorrate. Options and accessories areavailable to increase the ease of oper-ation and test accuracy of CTS55:

• OCXO reference oscillator forenhanced accuracy of all frequency-related test parameters (CTS-B1),

• small RF-shielded case (CTD-Z10) forDUTs to prevent spurious test resultscaused by local GSM, PCN or PCSnetworks, especially in the case ofbit error rate measurements,

• test SIM (subscriber identity module)to put a mobile telephone into ser-vice – even without a customer card(CRT-Z2).

Due to its great variety of functions, lowweight of less than 8 kg as well as smalldimensions and ease of operation, theapplications of CTS55 range from useas sales support for mobile phones to arepair tester in service departments orin production. Last but not least, the ex-ceptional price/performance ratio ofDigital Radio Tester CTS55 now makesit the most interesting solution forservicing tasks in the GSM/PCN/PCSmobile phone sector.

Michael Vohrer

REFERENCES

[1] Vohrer, M.: GSM Go/NoGo Tester CTD52 –The smallest base station in the world fortesting GSM mobile phones. News fromRohde & Schwarz (1995) No. 147, pp 4 – 6

[2] Mittermaier, W.: Module test with DigitalRadiocommunication Tester CMD52/55.News from Rohde & Schwarz (1995) No.149, pp 36 – 37

[3] Vohrer, M.: Low-cost Service Radiocommuni-cation Testers CMD50/53 for GSM/PCN/PCS mobiles. News from Rohde & Schwarz(1996) No. 150, pp 54 – 55

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Condensed data of Digital Radio Tester CTS55DUTs GSM, PCN (DCS 1800), PCS (DCS 1900)

mobile phones

Operating modes manual and fully automatic test sequence with printer report

Functions synchronization, registration, call setup, call clear-down, channel change, power change, echo test

Test facilities sensitivity (RxLev, RxQual), power, power ramping, frequency error, phase error,BER (RBER II, RBER IIb), FER, IMSI, IMEI

Reader service card 152/01

FIG 6 During receiver test, CTS55 simultane-ously indicates relevant bit error rates (RBER IIand RBER IIb) and frame error rate (FER) as wellas RxQual and RxLev values sent back by mobilephone for monitoring.

FIG 5 Power ramp with inserted tolerancewindow makes it easy to detect deviations fromnominal curve.


Increasing communication traffic and adensely occupied frequency spectrumin the lower frequency range are thereasons for resorting to higher andhigher frequencies. The transition fromvoice or data transmission to digital picture transmission requires widerbandwidth per channel and denserspectrum occupancy. For T&M thesetrends call for higher frequency limitsfor characteristics that up to now wereonly necessary for the lower frequencyrange. Rohde & Schwarz takes thesetrends fully into account by offering two

new members of the FSE spectrum analyzer family [1; 2]: FSEM and FSEK

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Spectrum Analyzer FSEM/FSEK

Fast spectrum analysisnow through to 40 GHzThere are new additions to the FSE spectrum analyzer family: in Spectrum Ana-lyzer FSEM Rohde & Schwarz has now moved into the microwave range throughto 26.5 GHz and, with FSEK, for the first time through to 40 GHz. New on theworld market is a vector signal analyzer option which allows modulation analy-sis of digitally modulated signals at these frequencies. Standards of measurementspeed, precision, dynamic range and spectral purity, set by FSE in the RF range,are of course maintained by the latest members of the family in the microwaverange.

FIG 1 SpectrumAnalyzer FSEM up to 26.5 GHz andFSEK up to 40 GHzPhoto 42 573

FIG 2Frequency range

of eight FSE models

FSEM30

FSEK20

FSEK30

FSEM20

FSEB20

FSEB30

FSEA20

20 Hz 9 kHz 3.5 GHz

7 GHz

26.5 GHz

40 GHz

FSEA30

(FIG 1). The FSE family consists of eight models that differ in performanceand frequency range (FIG 2). Theupper frequency limit of the FSEM models is 26.5 GHz (overrange up to27 GHz), that of the FSEK models 40 GHz. The performance of models20 is that of the high-end of the mediumclass, whereas models 30 are absolutetop-class models.

Dense spectrum occupancy places high demands on the transmitters andreceivers of a communication system.Interference of adjacent channels andother radio services has to be avoided.Adjacent channels may be impaired inparticular by the modulation spectrumand by intermodulation at the trans-mitter, other radio services by spuriousemissions or especially harmonics ofthe transmitter. For all communicationsystems these spectral characteristicsare subject to very stringent specifica-tions. A suitable spectrum analyzer istherefore required to verify the charac-teristics in development, production orservice. Inadequate characteristics of a measuring instrument, for exampletoo low a dynamic range, can be com-pensated by external units such as pre-amplifiers and switchable filters but willalways involve extra costs (additionalhardware and longer test times) and atthe same time the risk of erroneousmeasurements.

Dynamic range

Dynamic range is one of the key parameters of a spectrum analyzer. Dynamic range covers different charac-teristics such as sensitivity, overdrive


(1-dB compression), intermodulation,phase noise and display range. Micro-wave analyzers FSEM and FSEK of theFSE family offer excellent figures for allthe above-mentioned parameters.

A precondition for high dynamic rangeis high sensitivity to analyze weak sig-nals. To achieve high sensitivity, FSEMand FSEK operate with fundamentalmixing up to an input frequency of26.5 GHz, ie the input mixer uses thefundamental of the first LO to convertthe input signal to the first IF. Thus themixer yields low conversion loss, whichin turn is reflected in the noise figure (FIG 3). Above 26.5 GHz, FSEK mixeswith the fourth harmonic of the LO.Most spectrum analyzers use harmonicmixing at frequencies well below 10 GHz (6 to 8 GHz). So harmonics ofsignals might no longer be detecteddue to the reduced sensitivity of the analyzer. In this case an external pre-amplifier and a highpass filter for atten-uating the fundamental are required.The low noise floor also brings an advantage in speed: a wider resolution

sweep speeds – a considerable gain in time and thus a cost reduction in production for example.

In addition to sensitivity, large-signalbehaviour is important for dynamicrange, ie 1-dB compression, intermod-ulation-free range or harmonics sup-pression. For all three parameters mi-crowave analyzers FSEM and FSEKyield the same excellent characteristicsas low-frequency analyzers FSEA andFSEB. The 1-dB compression of the RFinput of +10 dB allows measurement ofvery weak signals in the presence ofhigh signal levels without impairing theweak signal. The signal path to the IF filters can be overdriven by 15 dBabove reference level. Overdrive indi-cations warn the user if the input signalis too high – also in the case of auto-matic operation from a controller. Thissaves the use of notch filters at the transmit frequency in the measurementof nonharmonics, for example, andmakes for a simplified test setup. Together with resolution bandwidth of 10 Hz, the third-order intercept point of+15 dBm yields an intermodulation-freerange of more than 100 dB. The resultof this is as follows: if several large RFsignals are present at the antenna con-nector of a mobile radio base station,for example, signals with a differencein level of up to 100 dB can still bemeasured without requiring notch filtersto suppress the high levels.

Especially if nonharmonics in adjacentchannels have to be measured, thephase noise of the internal oscillators is a decisive factor for dynamic range.Too much phase noise suppresses weaksignals or spectral components in theadjacent channel, but the spectrum an-alyzers of the FSE family are exemplaryin this respect too (FIG 4). It is note-worthy that the low phase noise in the vicinity of the carrier drops to 140 dBc per 1-Hz test bandwidth at 10 MHz. Even the phase noise of oscillators for transmitters or receiverscan be measured with sufficient dy-namic range – a major advantage inspeed and handling compared to the

usual test setups for phase-noise meas-urement.

Precision

As far as precision is concerned, micro-wave analyzers FSEM and FSEK show,like the other members of the family inthe RF range, characteristics that havenot been matched so far, ie frequencyaccuracy, level measurement accuracyand reproducibility of results.

Even at large frequency spans, fre-quency accuracy is attained by asweep with the first conversion oscil-lator locked to the internal or externalreference at each frequency. At rela-tively small spans from about 5 MHzmost spectrum analyzers use a free-run-ning YIG oscillator tuned by an analogsawtooth voltage. The nonlinearity ofthe YIG tuning characteristic has a direct effect on frequency accuracy.Things are quite different with the FSEfamily. Even for the maximum span of 27 or 40 GHz the tuning oscillator iscrystal-accurate at any frequency – andat that even for the minimum sweeptime of 5 ms. Frequency lines indicatedwith a marker can be displayed directwith high resolution and without intermediate steps – in the split-screendisplay simultaneously in a secondmeasurement window.

Like with FSEA and FSEB level meas-urement accuracy is also very high onthe agenda for microwave analyzers

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filter can be used to attain the same dis-played noise floor as with less sensitivespectrum analyzers. The double band-width results in a displayed noise floorthat is 3 dB higher but allows fourfold

FIG 4 Single-sideband phase noise of FSEMand FSEK at 500-MHz and 26.5-GHz input fre-quencies

FIG 3 Noise display of FSEM over whole frequency range measured with bandwidth of 1 MHz (top) and in range important for radiotransmission to 2.5 GHz


(FIG 5). For these analyzers too, Rohde& Schwarz gives the guarantee that amaximum total level error will not be exceeded – a claim unique amongstspectrum analyzers. The total error is aslow as 1 dB (up to 1 GHz) and 3.5 dB(at 40 GHz) in the whole temperaturerange. This is made possible for the firsttime by very stringent production toler-ances and internal calibration routinesfor absolute gain, the resolution filters(bandwidth and gain) and for the logamplifier characteristic together withcorrection data stored on each modulefor the frequency response of for exam-ple the attenuator, the YIG preselectorand the front-end. The guaranteed levelmeasurement accuracy often spares theuser an elaborate correction, eg withan additional power meter, providesmeasurement reliability and tolerances

Speed

Time is one of the most important costfactors, in development where productshave to be launched fast, or in produc-tion where products have to be manu-factured at high throughput and thuscost-effectively. Here too FSEM andFSEK set standards in many ways andhelp the user reduce costs by savingtime and thus become more competi-tive: the fast synthesizer allows a mini-mum sweep time of 5 ms up to 7 GHzand 150 ms over the whole frequencyrange at full level measurement accu-racy. With 25 pictures per second, pro-cedures can be analyzed practically inrealtime. Manual alignments can beperformed with an “analog feeling”.The 20-MHz A/D converter also allows display of short signals with highresolution (100 ns/div) thanks to themaximum bandwidth of 10 MHz. Thehigh computing power (586 PC with133-MHz clock frequency, transputernetwork and DSPs) yields very fast response times and data outputs on the IEC/IEEE bus even in the case ofcomplex functions such as phase noisemeasurement, power or adjacent-power measurement and optionally forseveral channels at the same time.

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can be fully utilized for the DUT insteadof reserving them for the measuring instrument.

The largely digital signal processing encompassing the resolution filters from1 Hz to 1 kHz, detectors and the fullysynchronous sweep ensures goodmeasurement reproducibility. Temper-ature and aging no longer have an effect. It is also noteworthy that meas-urement errors are not eliminated bybackground calibration during opera-tion but only at the request of the user.So there will be no unpleasant surprisescaused by an automatically triggeredcalibration routine.

FIG 5 Frequency response of FSEM up to 26.5 GHz (without correction by peaking function)

Condensed data of Spectrum Analyzers FSEM/FSEKFrequency range 20 Hz/9 kHz to 26.5/40 GHz

Amplitude measurement range –152/–142 to 30 dBm

Amplitude display range 10 to 200 dB in 10-dB steps, linear

Amplitude measurement error <1 dB (up to 1 GHz), <1.5 dB (1 to 7 GHz),<2 dB (7 to 18 GHz), <2.5 dB (18 to 26.5 GHz),<3.5 dB (26.5 to 40 GHz)

Resolution bandwidths 1 Hz/10 Hz to 10 MHz, in steps of 1/2/3/5

Calibration amplitude, bandwidths, demodulator characteristic

Display 24 cm (9.5“) colour or B/W TFT LCD, VGA resolution

Remote control IEEE 488 (SCPI 1994.0) or RS-232-C


Microwave analyzers FSEM and FSEKcan of course be extended to applica-tion-specific solutions with the same op-tions as the RF analyzers. Vector SignalAnalyzer Option FSE-B7 [2] deservesspecial mention since for the first timemodulation analysis of digitally or ana-log-modulated signals is now possiblealso in the microwave range in a singleunit.

Josef Wolf

REFERENCES

[1] Wolf, J.: Spectrum Analyzer FSEA/FSEB –New dimensions in spectral analysis. Newsfrom Rohde & Schwarz (1995) No. 148,pp 4–8

[2] Wolf, J.: Spectrum Analyzer FSE with OptionFSE-B7 – Vector signal analysis – indis-pensable in digital mobile radio. News fromRohde & Schwarz (1996) No. 150, pp 19–21


System architecture

Calibration System TS9099 (FIG 1) ismodular and upward-compatible, sosystems can easily be adapted to different user test requirements. Compared to manual measurement, automatic calibration produces con-siderable savings in time and addi-tionally read and write errors areavoided. The user can easily add new standard units to the basic equip-ment and connect new DUTs to thesystem.

The basic units of the calibrationsystem (FIG 2) are:

• signal generator,• spectrum analyzer,• modulation analyzer,• power meter,• precision attenuator,• system panel,• controller with printer,• software.

An uninterruptible power supply, peri-pherals and small units as well as racks,table and antistatic facilities completethe system.

System accuracy can be increasedconsiderably by means of a rubidiumfrequency standard regulated by a

interfacing of a DUT and on the otherfor switching electrical signals from aDUT to the measuring instruments andvice versa. Automatic and coordinatedinterconnection of the DUT with thevarious instruments within a calibrationroutine is also established via thesystem panel.

The test assembly is equipped with aselftest routine for checking and docu-menting the status of the system on power-up. The reference standardsused can be varied or exchanged. Thecharacteristic impedance used for RFmeasurements is 50 Ω. All RF connec-tions are BNC or N.

standard-frequency receiver. Of course,TS9099 can be connected to anyfrequency standard already used bythe customer. All measuring units of thecalibration system were selected so thatthe DUT parameters to be calibratedcan be determined at the prescribedaccuracy in the required ranges.

The system panel belongs to the basicequipment of the automatic system; itserves on the one hand for mechanical

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Calibration System TS9099

Automatic test equipmentcalibration to ISO 9000Rohde & Schwarz has developed the powerful Universal Calibration SystemTS9099 to enable fast calibration of a whole variety of RF measuring instrumentsin line with ISO 9000. This system was specially designed for signal generators,test receivers and radiotelephone test assemblies for frequencies up to 2 GHz. Thefrequency range can be extended at any time.

FIG 1 CalibrationSystem TS9099 forsignal generators, testreceivers, radiotele-phone test assembliesand similar equip-mentPhoto 42 188


System software

The state-of-the-art system software isinteractive (FIG 3), messages indicateincorrect operation. Menu guidancecan be selected in German or English.The software is divided into two parts:basic software and user-definablelibrary containing test routines. Aftersystem training, the user himself canwrite such routines. This library can beextended for any equipment with aremote-control interface by the user orRohde & Schwarz. The DUT permitting,test sequences can be automated usingthe software and the system panel.

Process control is effected by a user-programmable controller with IEC/IEEE-bus interface. This networkablecontroller can be equipped withstorage media such as a streamer orexchangeable harddisk. The measuringinstruments, the DUT (if remotely con-trollable) and the computer are linkedvia the IEC/IEEE bus or serial inter-faces. The controller steers the completetest sequence and stores and processes

test data. The customer can also orderyearly recalibration of the whole systemby an authorized center (eg Rohde &

Application

The TS9099 test system serves forcalibration of the following measuringinstruments:

• signal generators,• test receivers,• RF millivoltmeters,• power meters,• radiotelephone test assemblies,• spectrum analyzers,• frequency counters,• attenuators,• cables,• probes.

Measurements are made of all requiredDUT parameters such as carrier fre-quency, S/N ratio, RF level and power,attenuation, reflection coefficient,amplitude, frequency and phase modu-lation, modulation frequency, AF leveland AF total harmonic distortion as part

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of the guaranteed specifications. Aftercalibration, the results are displayed onthe screen of the system controller oroutput on a printer.

Jon Pedersen

Schwarz Cologne Plant). In addition, itis possible to conclude a maintenancecontract for regular inspection of thesystem at defined intervals.

Condensed data of Calibration System TS9099Frequency range 10 kHz to 2160 MHz (can be extended)

Level range –140 to 13 dBm (can be extended)

Types of modulation AM, FM, ϕM

Modulation frequency 1 Hz to 100 kHz

Power measurementPower range 1 µW to 100 mWFrequency 0 to 18 GHz

Test modes automatic, interactive

Interfaces IEC/IEEE bus, RS-232-C, TTL


FIG 3Softwareinterface

FIG 2 Block diagram of Calibration SystemTS9099 (options in yellow)

VSWR bridge

Frequency standard

Video distrib.

amplifier

Multi- meter

Scanner

Power sensor

VSWR bridge

System panel

HF

Switching matrix

RF attenuator

Modu- lation

analyzerRF

voltmeter

Signal generator

Spectrum analyzer

Generator

RF AFRF

AF IF Track gen.

Ref.

Power splitter

Har- monics filter

RFMod.

AF

IF

to DUT

Har- monics filter

CISPR generator


High computing power is a feature ofmany PCs, but applications outside thecomfortable office enviornment soonseparate the men from the boys. SystemProcessor MERLIN GR2000 (FIG 1),which is of course compatible with theindustry standard, not only offers highcomputing power but is also suitable

for use under extreme environmentalconditions. It is of sturdy construction,has low RF emission and low suscep-tibility to EMI, is rackmountable andoperates reliably at temperatures from0 to 50 °C.

The basic model of GR2000 offers theusual performance characteristics of astandard PC: plug-in Pentium CPU card(currently 133 MHz), 16-Mbyte RAM(expandable to 256 Mbytes), PCI VGAgraphics card, CD-ROM drive, 31/2-inch disk drive, 1-Gbyte exchangeable

harddisk and a PCI Ethernet card.Thanks to the modular design andversatile expansion capabilities, thesystem processor can be tailored tocustomer’s specific application needs.A wide variety of special, intelligentinterface cards – eg fax, video framegrabber cards and encryption cards –are available. The passive backplanecan accommodate up to eight plug-incards. This design allows, among otherthings, various CPU upgrades, and soguarantees that the equipment is future-proof. The basic configuration providesfive additional slots with PCI or ISA busfor further expansion.

MERLIN version GR2000X is equippedwith EMC filters at its inputs and outputs(FIG 2) and has special shielding. Thismeans low emission and low EMIsusceptibility. RF shielding is effectiveboth for radiated and conducted inter-ference and ensures interference-freeoperation in two respects. On the onehand, the system processor is not affect-ed by strong EMI, and on the other, the unit itself does not affect equipmentsensitive to EMI (eg receivers). The

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System Processor MERLIN GR2000

Powerful processor standstoughest conditionsSystem Processor MERLIN GR2000 is now replacing MERLIN GR856, which hasbeen used for many special applications all over the world. MERLIN GR2000meets the same stringent environmental conditions but with more performance, amore advanced bus system and better expandability than GR856. The enhancedprice/performance ratio will make GR2000 an attractive proposition for new applications, whether stationary or mobile.

FIG 1 Rugged System Processor MERLINGR2000 can work effortlessly even in toughestconditions of vibration, impact and shock.

Photo 42 561


filters at the serial and parallel inter-faces make MERLIN ideal for use inapplications that encounter extraordi-narily high levels of spurious emissions.

The enclosure is of an extremely sturdyconstruction. MERLIN can even be usedin environments exposed to waterspray and – thanks to a pressurecooling system with the air sucked invia filters – in dust-laden atmospherestoo. The frame is reinforced anddesigned to withstand extremely highmechanical stress. This ensuresproblem-free operation under extremevibration, impact and shock loads,which occur in vehicles and onboardships. MERLIN will also operatesmoothly in rough terrain or on theopen sea. The 19-inch rack model, analternative to the bench model, is parti-cularly suited for use in vehicles.MERLIN is compatible with all conven-tional keyboards and monitors. Rohde& Schwarz also supplies special key-board and monitor versions for moresophisticated requirements.

A choice of power supplies is availablefor System Processor MERLIN. As analternative to the standard version, apower supply that satisfies the stringentrequirements for use onboard ships inline with STANAG 1008 is available.This version is immune to large voltagefluctuations and AC-line spikes of up to2.5 kV. Moreover, the user can choosebetween AC and DC power supplies.

The exchangeable harddisk affordsmaximum flexibility and data security.As a boot medium, it enables fast and convenient loading of another operating system or of programs forvarious applications and requirements.Sensitive information can be conven-iently stored in a safe place. Specialstorage media are available forapplications subject to extremely highlevels of vibration.

With the CD-ROM drive, which is in-cluded as standard, Rohde & Schwarzis taking a forward-looking approachto industrial PCs. This feature provides

access to the world of multimedia andsimplifies the installation of modernoperating systems [1].

Its EMC compatibility means that Sys-tem Processor MERLIN can be used inthe immediate vicinity of radio trans-mitters and their antennas. In conjunc-tion with message-handling programsand special, intelligent interfacemodules, data transmission can beimplemented and combined [2] using awide variety of media such as HF, VHFand UHF radio links, telephone linesand satellite links. The message-handling programs support the trans-mission of fax files and vido stills [3]and optimize the use of e-mail net-works. The familiar office environmentcan thus be connected to variouscommunication networks.

MERLIN has proven itself as a systemprocessor and data terminal in a largevariety of applications implementedby a great number of customers. Func-tioning as a data terminal, MERLIN is operated with an ICOM-8 card. Thisprovides eight serial channels, easesthe workload of the CPU as it has itsown processor, and also supports 5-bitteletype mode (Baudot code). It allowsmore instruments to be simultaneouslycontrolled than is the case with a con-ventional PC. MERLIN can thus utilizeseveral media at a time and avoid de-lays in data transmission. An encryp-tion card can be fitted to make thetransmission of sensitive data more secure.

Thomas Kneidel

REFERENCES

[1] Maurer, P.; Völker, K.: Multimedia communi-cation with System Processor MERLIN. Newsfrom Rohde & Schwarz (1993) No. 142,pp 27– 28

[2] Maurer, P., Völker, K.: Integration of moderndata terminals in radioteletype networks.News from Rohde & Schwarz (1994)No. 146, pp 48 – 49

[3] Hackl, J.; Kühn, G.: Colour video stillsspeedily and reliably by shortwave. Newsfrom Rohde & Schwarz (1992) No. 139,pp 42–43

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Condensed data of System Processor MERLIN GR2000Processor

CPU plug-in Intel Pentium processor board,133 MHz, 16 Mbytes

Graphics card PCI VGA, 2-Mbyte RAMExchangeable harddisk 1 GbyteDrives 3.5-inch disk, 1.44 Mbytes; CD-ROM

InterfacesStandard I/O 2 x COM, 1 x LPT,

filtered I/O interfaces (GR2000X)Free slots 1 x PCl, 3 x ISA, 1 x PCl/ISA

Network card PCl Ethernet


FIG 2 EMC filters in serial and parallel interfacesof System Processor MERLIN GR2000X

Photo 42 568/1


The technical safety of an ATC radiosystem depends on a variety of

features and measures at the deviceand system level. They include low unit downtimes, equipment redun-dancy, frequency planning and solu-tions to collocation problems. Modernsystems also call for central controland monitoring with special functionsto ensure link reliability, convenienceand cost efficiency calculated over thesystem’s lifetime.

flexibility and offers the system plannerdifferent techniques and special fea-tures.

Parallel technique. This allows normaloperation of the radio equipment viaconventional interfaces.

Digital REM BUS technique. The newmodel (.03) of REM BUS Drive Unit

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Series 200 and 400U radio equipment

Innovations in ATC radio-communications: RCMS and8.33-kHz channel spacingReliability has top priority in ATC radiocommunications as human lives are atstake. Central and flexible remote control and monitoring systems (RCMS) as wellas the 8.33-kHz channel spacing planned for 1998 contribute to safety. For thisreason Rohde & Schwarz has logistically upgraded its ATC radio equipment: Series 200 now comes with RCMS and 8.33-kHz channel spacing. Series 400U is also available with 8.33 kHz. Thus the customer is already provided with ultramodern and future-proof solutions.

FIG 1 VHF system with eight single-channel Receivers EU231A and single-channel Trans-mitter SU251 as well as channel-specific RCMSwindow (example: channel 003/130.1 MHz,separate transmitters and receivers each in auto-matic 100% standby mode) Photo 42 570

Remote Control and Monitoring System RCMS

The RCMS especially developed byRohde & Schwarz for Series 200 radioequipment [1] offers the user differentways of remote control (interfaces,transmission techniques) as well as integration of auxiliary tools (options,add-on units) and user-friendly software(FIG 1). Any ATC radiocommunicationssystem is subject to customer-definedspecifications and constraints for all itssubsystems such as radio, operationand control or voice switching. RCMSmeets these requirements thanks to its


GV201 allows control at PC COMinterfaces via RS-232-C (FIG 2). Thecorresponding RCMS software can be used for single-channel and multi-channel Series 200 radio equipmentand is downward compatible with single-channel systems installed so far.Altogether 30 control and monitoringfunctions can be transmitted per trans-ceiver channel.

Audio inband technique via four-wiretelephone lines. With this option theleasing fees for point-to-point telephonelines, especially for transceivers, can be reduced considerably. A carrier fre-quency (2040 or 2440 Hz) is nestedinto the two bidirectional audio spectra(FIG 3). The combination of 4FSK andAM modulation as well as the use of adigital 24-bit signal processor with highcomputing power of 20 MIPS allowsaround 20 remote control and monitor-ing functions including the time-criticalfunctions PTT and AGC/squelch to bemodulated and demodulated.

Hybrid technique. The above-men-tioned techniques can also be com-bined for special system requirements.

Thanks to these remote control andmonitoring system features, technicalsupervisors benefit from the follow-ing:• central configuration of the radio

system,• continuous tests,• display of station and channel status,• manual and automatic radio redun-

dancy,• RF tests at any operating frequency

of receiving systems,• remote error analysis partly down to

the functional unit,• permanent result logging,• efficient deployment of personnel.

All this is not limited to the airport butcan be used country-wide: thanks tomodems or the inband technique thetechnical supervisor can be contactedpractically anywhere and at any time.Rohde & Schwarz is offering specialsupport for the supervisor with Mainte-nance and Service Package X-LINK(Express Link). With this extremely economical product, software updatesand functional checks (error analysis) of a radio system are performed at Rohde & Schwarz headquarters in Munich via telephone lines after re-ceiving the customer’s request and per-mission to access the equipment – nomatter whether the airport is in theSouth Pacific or in Siberia.

Reorganization of frequency management

Increasing air-traffic volume and the pre-dicted frequency demand for voice andradio data transmission in the VHF rangefrom 118 to 137 MHz create the needfor fast and radical reorganization offrequency management. The operation-al requirement for undisturbed channelswould not be met by merely halving thepresent channel spacing from 25 kHzto 12.5 kHz, so the International CivilAviation Organization ICAO has cometo the following decisions after testsconducted by the British ATC authority(CAA/NATS) as well as feasibility stud-ies and specifications by different com-mittees (eg EUROCAE, ETSI) with activeparticipation by Rohde & Schwarz:• A VHF channel spacing of 8.33 kHz

(voice) and 25 kHz (voice and data)will be introduced.

• Operation in Europe will belaunched on 1 January 1998 in se-lected air corridors.

• Modulation will be AM A3E (double-sideband modulation, DSM).

• Ground single-channel radio equip-ment will be for 8.33 or 25 kHz.

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Test generator (RF)

Workstation

REM BUS

AF/PTT AF/PTTRF RF

Voice communication switching system

RS-232-CAF/PTT distribution to operators

AF/PTT distribution to operators

Transmit station

Modem

Telephone line

Supervisor

RS-232-C multiple COM card

Modem

Telephone line

Modem


REM BUS Drive Unit GV201(.03)

7

Transmitter SD/SU2...

Transmitter SD/SU2...

14

Filter/combiner (multicoupler) network

REM BUS

AF/PTT AF/PTTRF RF


RS-232-CAF/SQL distribution to operators

AF/SQL distribution to operators

Receive stationModem


REM BUS Drive Unit GV201(.03)

Test generator (RF)

7

Receiver ED/EU2...

VHF-UHF multicoupler

VHF-UHF multicoupler

Receiver ED/EU2...

14

RX REM BUS

RX REM BUS

FIG 2 Digital control and monitoring system(RCMS) for separate VHF/UHF transmit and re-ceive stations with 14 radio channels

FIG 3 Analog (AF) inband RCMS for VHF-UHFradio station with transceivers with one redun-dant (F1) and one normal channel (F2)

Radio station

AF, PTT, SQL from/to operators via voice communication switching system

Supervisor

Telephone line

44

AF distributor

TX/RX B F1

TX/RX A F1

TX/RX A F2

Filter/combiner (multicoupler) network

Control

F8

Transceiver

Highly decoupled antenna system

4

2

2

2

2

2

2

AFRF(TX) RF(RX)

Control

for TX/RX A/B F1

Control for

TX/RX A F2


• Airborne transceivers will haveswitchover capability between 8.33and 25 kHz.

Switchover between 8.33 and 25 kHzalso has to be possible for ground VHFmultichannel radio equipment such asfor emergency standby or special tasks(SAR, defence).

ATC operators in key European areas(southern part of Great Britain, theBenelux, France, Germany, Switzer-land, Austria and northern Italy) arenow asked to invest on the basis of thedecisions taken with a view to imple-menting the new frequency channels inground radio control centers. Airlineswill have to retrofit part of their fleets.

The 8.33-kHz requirement has in par-ticular implications for the followingcomponents:• synthesizers for transmission, recep-

tion and test (channel setting andhigher frequency stability),

• receivers (higher selectivity throughIF crystal filters),

• transmitters (lower modulation uppercutoff frequency),

• operation and display (adaptationof hardware, device-specific firm-ware and system software).

Innovations in Rohde & Schwarz radio equipment

The new units of Series 200/single-channel comprise a new, universalsynthesizer. Models of VHF ReceiverEU231A/D and VHF TransceiverXU221/XU251 are now available for8.33 or 25 kHz with corresponding IFfilters. For the transceivers, a modulatorextension is additionally provided for the 8.33-kHz specific frequency response. This modulator extension for8.33 kHz is available as an option for VHF Transmitters SU221/SU251.To guarantee retrofitting from 25 to8.33 kHz (or vice versa) with mini-mum logistics and service, the IF filtersas well as the modulator extension are equipped with connectors. A test

generator for receiving systems using8.33-kHz channel spacing is anothernew option.

Series 200/multichannel VHF andUHF radio equipment that can beswitched to any frequency within the25- or 8.33-kHz channel spacing is cur-rently being developed (first digital ATCreceiver) and will be available in timebefore 8.33-kHz operation is started.

New in Series 200/RCMS too: REMBUS Drive Unit GV201 and RCMS software are of course tailored to thenew techniques. Thus they comprise im-portant components and performancefeatures for PC-controlled RCMS. Oneof the most attractive innovations ofRCMS is Service and MaintenancePackage X-LINK mentioned already.

As part of Series 400U, which is basedon the successful Series 400 [2], Rohde& Schwarz offers the following new 25-and 8.33-kHz-compatible unit types forcivil and military multichannel appli-cations: Transceivers XU452U8 (VHF)and XT452U8 (VHF/UHF), TransmittersSU452U8 (VHF) and ST452U8 (VHF/UHF) as well as Receivers EU458U (VHF) and ET458U (VHF/UHF). AnAF/telephone Interface is available as

an option for 8.33-kHz transmitters andtransceivers. The operating software forthe radio equipment is of course alsodesigned for 8.33-kHz operation.

Optimum coordination between all persons involved in introduction of the8.33-kHz channel spacing (ATC opera-tors, airlines, service, supply industry,etc) guarantees in these times of reor-ganization that restrictions of air trafficor impairment of flight operations in theparallel 25-kHz ATC sectors are re-duced to a minimum. Rohde & Schwarzcontributed to this by committing itselfearly to the definition phase and by developing, producing and supplyingnew radio equipment in good time. After just one year of development, the8.33-kHz technique could be launchedin June 1996 with 100 units from eachof the Series 200 and 400U radioequipment.

Hans-Günther Klarl; Martin Kessler

REFERENCES

[1] Klarl, H.-G.: Series 200 VHF single-channelradio equipment – The new dimension inATC communication. News from Rohde &Schwarz (1993) No. 140, pp 4–7

[2] Haller, J.: Series 400 VHF/UHF radio setsfor air-traffic control. News from Rohde &Schwarz (1982) No. 96, pp 4–7

Articles

Innovations in Series 200 and 400U radio equipmentSeries 200

VHF single-channel receiver 8.33- or 25-kHz spacing, and transceiver depending on version

VHF single-channel transmitter 8.33 kHz (with Modulator Extension GM201C8)or 25 kHz

Multichannel units currently being developed

REM BUS Drive Unit GV201 (.03) RS-232-C interface for PC-COM cards, conversion to REM BUS

Operating Software GC201-S (.03) combined version for 8.33 kHz and 25 kHz

Test Generator GT231T1 (.22) 8.33-kHz and 25-kHz compatible,for single-channel and multichannel units

4-carrier offset according to ICAO with standard synthesizer

Series 400U

VHF + VHF/UHF multichannel receiver 8.33 kHz/25 kHz switchover

VHF + VHF/UHF multichannel 8.33 kHz/25 kHz switchover (with GI419U)transmitter and transceiver

AF/Telephone Interface GI419U module for 8.33-kHz compatible transmitters andtransceivers

Operating Software GB406-S combined version for 8.33 kHz and 25 kHz



With its modular design the compact12-kg TV Test Receiver EFA (FIG 1) is extremely versatile and made for easyupgrading. In addition to the micropro-cessor module fitted as standard andthe modules of the respective basic EFAmodel, another five functional modulescan be accommodated (FIG 2). Everyuser can thus configure a model to suithis specific requirements or upgradethe basic model at a later date.

Basic models

The first member of the EFA family is theanalog TV test receiver with selectivereceiver section. It receives amplitude-modulated TV signals to all commonstandards, selects the TV channel and converts it to IF. Picture and soundsignals are then demodulated by theanalog demodulator. Sound is demod-ulated according to the intercarriermethod, where the vision carrier is

multiplied by the sound carrier and the intercarrier thus obtained is select-ed and frequency-demodulated. Theadvantage of this is that incidentalphase modulation from local oscillatorsas provided in every TV receiver doesnot appear in the demodulated audiosignal, whereas that from the visionmodulator is reflected in the demodulat-ed audio signal. TV Test Receiver EFAdetects this interference and is thereforesuitable for measuring and monitoringthe sound quality of received signals.The frequency-demodulated audio sig-nals are brought out at balanced out-puts. For measuring incidental carrier

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TV Test Receiver Family EFA

Top fit fordigital televisionSmall-size, compact, future-oriented, upgradable – this is how TV Test ReceiverFamily EFA shows its true self. With this family Rohde & Schwarz has created a test platform that can easily keep pace with rapid developments in television.Before the official start of digital video broadcasting, Rohde & Schwarz can already offer the world’s first demodulator for QAM signals which is able to perform all the measurements required on cable digital channels. An analog TV test receiver – either broadband or selective – is available for monitoring the previous TV channels. Digital and analog functions can also be combined in asingle unit, which can be expanded by adding options.

FIG 1TV Test Receiver EFA, allround specialist for

measurements on analog and digital TV signals –

seen here in headend stationPhoto 42 575


phase modulation (ICPM), TV Test Receiver EFA provides a quadrature-demodulated vision carrier signal. Inconjunction with an internal or externalzero reference pulse and an oscillo-scope or video analyzer, it allowsquantitative determination of ICPM.

The analog TV Test Receiver EFA meas-ures all important RF transmission pa-rameters and displays them on anLCD (FIG 3):• power and voltage of vision carrier

in dBm, dBpW or µV/mV, dBµV,• vision carrier frequency,• vision/sound carrier level ratio,• vision/sound carrier frequency spac-

ing,• FM sound carrier deviation,• FM pilot deviation,• pilot frequency.

Depending on the model, Test ReceiverEFA demodulates TV signals of stan-dards B/G, D/K, K1, I or M/N. In ad-dition to a constant video group delay,implemented in each receiver model,TV Test Receiver EFA features group-delay correction that depends on the respective standard and is available for all worldwide TV standards.

An optional NICAM demodulator isavailable for decoding the digitalQPSK-modulated sound carrier to NICAM 728 standard. Further options(functional modules) are in develop-ment.

In addition to the model with selectivereceiver section, the analog TV test re-ceiver is also available with a broad-band receiver section. In single-chan-nel applications it is used for measure-ments directly on the source. Typical examples are measurement of the quality data of TV transmitters andtransposers in single-channel mode aswell as monitoring radiated RF sig-nals. A Nyquist demodulator ensuringsystem-compatible demodulation of thegenerated signals is used for these applications.

Further functional modules can be add-ed to the broadband TV test receiverjust as to the selective one.

Another member of the EFA family is theDVB test receiver with QAM demod-ulator. It is used for measurements ondigital channels in cable-TV networks.Instead of an analog demodulator, ademodulator for quadrature amplitude-modulated (QAM) signals – fully com-patible with the DVB standards [1] – isused in this case for processing theDVB-C channel converted to IF. The out-put signal is then in the form of a serialor parallel MPEG2 transport stream [2].

The QAM demodulator measures thefollowing parameters separately, per-forms calculations [3] and outputs the results on its display in line with re-quirements of the DVB MeasurementGroup [4]:• constellation diagram,• RF level,• signal/noise ratio,• bit error rate,• amplitude imbalance,• carrier suppression,• phase error and phase jitter,• modulation error ratio (MER).

The constellation diagram (FIG 4),which is graphically displayed andmathematically evaluated by a signalprocessor, supplies the most importantinformation on QAM signals. To ensurethe required statistical reliability for the evaluated parameters, about1,000,000 I/Q values are considered.

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FIG 3 Screen display for analog TV test receiv-er mode

FIG 2 Block diagram of TV Test Receiver EFA(basic models shown in blue, functional modulesin yellow). Receivers can be configured to suitspecific application.

Attenuator 0 to 55 dB

Selective receiver section

Selective RF input

IF inputReceiver section with tracking selection

Attenuator switch

Broadband receiver section

Broadband RF input

IF input

Analog demodulator for vision and

intercarrier sound

Video Audio (FM)IF sound

IF vision

NICAM demodulator

DSP analysis

IF output

IF

IF

QAM demodulator

MPEG2 transport stream

LCDRS-232-C IEC/IEEE bus Printer

Micro- processor

Receiver section of broadband demodulator model


The QAM demodulator can be fittedwith up to three SAW filters so that notonly 8-MHz QAM packets can be pro-cessed with 64QAM which is almoststandard today, but also packets of 4 or 2 MHz. Thanks to the versatile configuration possibilities of the QAMdemodulator, 4QAM to 256QAM canbe selected for all current methods.Among many other features, error pro-tection can be switched off and the roll-off factor selected. A built-in noise generator is available for determiningthe noise margin.

It is of course possible to equip the testreceivers for the measurement of bothanalog and digital TV signals. The mod-

Uses

The broadband TV test demodulator isideal for the precise measurement andmonitoring of the quality data of TVtransmitters and transposers. The selec-tive receiver model is required formeasurements in cable-TV networks.For this application the combinationalunit with analog and QAM demodula-tor is recommended. The powerful testreceiver family is of course also suitablefor applications in development labs,quality management and productionmonitoring.

With TV Test Receiver Family EFA fromRohde & Schwarz an enormous stephas been made towards digital videobroadcasting, whilst taking full accountof previous TV standards. The programwill be continuously expanded by newfunctional modules to open up furthersectors of digital television.

Christoph Balz; Ernst Polz;Walter Fischer

REFERENCES

[1] European Telecommunications Standards In-stitute ETSI: Digital broadcasting systems fortelevision, sound and data services; framingstructure, channel coding and modulationcable systems. Draft prETS 300 429 (1994)

[2] DVB Technical Module’s Ad-hoc Group Phys-ical Interfaces: Interfaces for CATV/SMATVheadends and similar professional equip-ment. 10th working draft DVB-PI-154 (1995)

[3] Balz, C.: Effiziente Ermittlung von Qualitäts-parametern quadraturamplitudenmodulierterSignale beim Digitalen Fernsehen (DVB).Fernseh- und Kinotechnik No. 5 (1996), pp 249–252

[4] DVB Technical Module’s Ad-hoc Group onTest and Measurement: MG 66 Rev. 4(04/1996)

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ular design allows optimum customiza-tion and the configurations describedabove are only a few among many.

Interfaces

EFA features a large LCD for display ofuser information, measured values andgraphs. Hardkeys and softkeys ensuregreat ease of operation. The micropro-cessor module provides a variety ofinterfaces; the receivers can be remote-ly controlled via IEEE bus or RS-232-Cinterface and come with a printer con-nector. The demodulated sound can be monitored via a built-in loudspeakeror headphones.

Condensed data of TV Test Receiver Family EFAFrequency range 47 to 862 MHz

Inputs RF, IF

Input impedance, RF 50 or 75 Ω

Input voltage rangeSelective analog TV test receiver 30 µV to 1000 mVSelective QAM receiver 100 µV to 700 mVBroadband analog TV demodulator 10 to 2500 mV

Outputs IF, controlled

Loudspeaker, headphones adjustable volume, can be switched off

Interfaces IEEE 488, RS-232-C, Centronics

Nyquist test receiverInputs external zero reference pulseOutputs video, Q signal, audio balanced,

audio unbalanced, headphones

QAM demodulatorSpecifications compatible with DVB guidelinesOrder of QAM 4, 16, 32, 64, 128 or 256Rolloff factor 0.15 to 0.30, selectableInternal noise generator 12 to 62 dB C/N, adjustableOutputs parallel or serial MPEG2 transport stream,

serial data/clock before error correction


FIG 4 Constellation diagram in QAM demod-ulator mode; result hold time adjustable from 2 ms to infinite


MPEG2 Generator DVG

MPEG2 Generator DVG (FIG 1) is asignal source for MPEG2 transportstreams. The structure of these streamsand the data reduction methods em-ployed were developed and standard-ized by MPEG (Moving Picture ExpertsGroup) and the DVB (Digital VideoBroadcasting) project. A main featureof the transport stream is that it contains

several programs, each consisting ofseveral substreams (video, audio anddata signals). Programs are no longercombined at RF frequencies after themodulator, as is the case with con-ventional TV techniques, but producedat the baseband in the form of a program and signal multiplex.

DVG generates these multiplex signalsand is a favourably priced and com-

pact alternative to expensive MPEG2encoders with multiplexer and externalstandard generators. It is ideal for test-ing and commissioning MPEG2 trans-mission links and may be used as a substitution signal source in the case ofprogram failures or for adjusting andtesting decoders and TV sets. SinceDVG takes its signals from RAM andthey can be played back time and timeagain without any “wear and tear”, thegenerator is predestined for applica-tions where continuous operation is required. These features make DVG a practical, high-availability signalsource wherever MPEG2 signals are to be found.

MPEG2 signal structure

MPEG2 signals are digitized video andaudio signals that have undergone con-siderable data reduction. The MPEG2standard permits several data reduc-tion methods to be used [1]. A mainfeature of video data compression isthat in most cases only data variations(differential video) are transmitted. Tomeet this requirement, the signals gen-erated by DVG consist of continuouslyrepeated moving picture sequences. Toavoid discontinuities at the end of eachsequence, the following should beborne in mind: the programs in thetransport stream are assigned differentpresentation time stamps (PTS) and decoding time stamps (DTS), enablingthe decoder to determine the sequenceof the pictures to be transmitted and to synchronize them with the accom-panying audio signals. Another timemarker, the program clock reference (PCR), is used as a reference. If thesame unchanged sequence were per-manently repeated without time stamps,there would be “time jumps” and alldown-stream equipment would have tobe resynchronized. The time stamps foreach program are therefore continuallyupdated in DVG and a continuous signal like that produced by an en-coder is generated, although the sceneis repeated over and over again (FIG 2). Only the use of continuoustransport streams such as these ensures

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MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMD

Test equipment for digital TVin line with MPEG2A new TV standard is about to be launched worldwide. Thanks to digital technol-ogy many more programs can now be broadcast and flexible scrambling offeredwithout the need for more bandwidth. Rohde & Schwarz supplies the test equip-ment that guarantees the quality of these digital TV transmissions received via a set-top box: MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMD.

FIG 1MPEG2 GeneratorDVG and Measure-ment Decoder DVMDwith TV monitorshowing decodedpicture and menu displayPhoto 42 498/1


smooth and reliable tests on MPEG2terminal equipment and transmissionlinks.

Signals generated by DVG

As FIG 2 suggests, some of the DVGtransport streams also contain live se-quences, ie video and audio signals,whose quality cannot be determined bymeasuring equipment but only by eye.As data-reduced signals have little orno redundancy, even a small number of bit errors may impair transmissionquality, particularly in areas where thepicture is changing. Therefore live sequences are essential for checkingthat transmitters and decoders are oper-ating correctly.

In addition to transport stream transmis-sion, analog signal processing in theterminal equipment also has to bechecked. D/A conversion in the decod-ers and adjustments of the picturegeometry in TV sets are normally testedwith video stills and the analog sound-signal path has to be adjusted or testedas well. DVG provides all essential test patterns and analog sound signalsrequired for these tests. The Rohde &Schwarz codec test pattern (FIG 3) andthe standard sound sequence CCITT0.33 are ideal for fast, automatic testswith video and audio analyzers.

This test pattern created by Rohde &Schwarz not only covers all ana-log measurements but simultaneouslychecks whether the MPEG2 trans-mission is OK or whether only the lastdecoded picture is displayed by the decoder. This check uses four white

areas rotating in each field and a white spot moving backward and forward across 24 frames displayed onthe screen. The loss of frames duringtransmission is indicated by irregularflicker of the rotating areas and by a halting movement of the white spot.The moving spot may also be used for delay measurements.

The transmission of data in the MPEG2multiplex is still an open question – evenamong broadcasters. Many data ser-vices could certainly be envisaged, butviewers will still, first and foremost,want teletext facilities in the future. Sothe transmission of teletext data has tobe checked as well. In this case DVG inserts teletext pages in the form of data packets into the transport streammultiplex.

Even all these signals do not exhaustthe capabilities of DVG. When a key-board, a mouse and a VGA monitorare connected, DVG becomes a PCwith additional signal generation fea-tures. For instance, with the aid of theStream Combiner® program packet,the MPEG2 specialist is able to gener-ate his own signals and make specialsettings in the system information data.Even errors may be included in thetransport stream.

Simple operation andmultifunction interfaces

All the main configuration data of thetransport streams are shown on the in-tegral LCD. Normally the data shownby the LCD will be sufficient, but if moredetailed information is required a

printer or VGA monitor can be connect-ed. In this case all the information in thetransport stream is available at thepress of a button. In addition to the RS-232-C interface, DVG also has aPCMCIA adapter. This adapter, thesame as that provided on every laptop,may be used for connecting SCS inter-faces, network cards, exchangeableharddisks or a CD-ROM drive forstoring signals.

The selected transport stream is avail-able at three DVG outputs. The TS par-allel output on the front panel is a syn-chronous, parallel LVDS interface. Thelevel at this output was set to the upperlimit of the DVB standard A010 [2] sothat at least two devices can be con-nected. Two devices may also be con-nected to the two serial, asynchronousoutputs (TS ASI), one on the front, theother on the rear of DVG. These twotypes of interface have now becomethe de-facto standards.

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All these signals, interfaces and con-figuration capabilities make DVG notonly a compact but also a universalMPEG2 signal source and thus an essential tool for measurements toMPEG2 and DVB.

FIG 2 Continuous PCR, PTS and DTS time stamps in repeated sequences

FIG 3 Rohde & Schwarz codec test pattern

PCR PTS DTS


MPEG2 Measurement Decoder DVMD

By monitoring and analyzing theMPEG2 transport stream, DVMD (FIG 1) performs a completely new kindof measurement task that has arisen because of the introduction of digitalTV. The measurements are intended toensure smooth interworking of all com-ponents in a DVB transmission network.DVMD also provides information aboutthe contents of the transport stream and decodes the programs containedin them. Results of the protocol analysiscan then be compared to the decod-ability of video and audio signals. Themeasurement decoder not only pro-vides comprehensive information aboutthe quality of the transport stream butmakes the new technology transparentso that reliable use is ensured.

No way out for errors:protocol monitoring online

Comprehensive, highly integratedhardware combined with a powerfulsignal processor system is the basis for continuous and comprehensivemonitoring and analysis of a transportstream. Analysis is always performedin realtime. Not only are substreams or individual programs monitored, theintegrity of the whole transport stream is checked. This makes it possible todemonstrate that timing is correct andcontents of protocols and parametervalues are complied with during trans-mission as well as with lab measure-ments.

Monitoring and analysis of the trans-port stream are based on the guidelineslaid down by the Measurement Groupof the Technical Module of the Euro-pean DVB project [3]. The tests definedin the guidelines are classified in termsof three priority groups according totheir importance. First-priority testscheck synchronization of the transportstream and program access. Tests inthe second priority group identify transmission errors and check time references in the elementary streams,

while tests of the third group monitorservice information for compliance withDVB guidelines.

All three groups are taken into accountby DVMD when the transport stream ismonitored. If an error occurs, detailedinformation that depends on the type oferror is output so that the error sourcecan be pinpointed. The ability to trigger

on a specific or any type of error (trigger on error) is also based on this monitoring system. In this case thetransport stream before and after thetrigger event is recorded and can beoutput via a serial interface for furtheranalysis.

This online measurement capability allows the network operator in partic-ular to determine the data rates of thetransport stream, programs and ele-mentary streams, which is a significantform of analysis. Data rates indicate the network load and determine trans-mission costs. They are not derivedfrom service information in the trans-port stream but computed online.

Decoder unit:essential enhancement plus second test set

DVMD combines a test set and decod-er in one unit and uses decoding as anadditional test method. As a result youcan directly “hear and see” what resultsmean. Video and audio signals areavailable in analog and digital form:• analog video in PAL, NTSC or

SECAM (two outputs),• analog video in Y and C,• digital serial video (ITU-R 601/

270 Mbit/s),• analog audio L /R (two outputs

each),• digital audio AES/EBU.

The audio-visual content of a transportstream is laid bare and can be passedon in decoded form.

No restrictions forscrambled programs

DVMD may also be used for scram-bled programs. These have no effecton protocol monitoring since the relevant data are not scrambled. Acommon interface defined by the DVB project [4] is available for decod-ing scrambled programs. With the aid of a key card, obtainable from the broadcaster, even scrambled pro-grams can be analyzed.

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FIG 4 Error statistics from MPEG2 Measure-ment Decoder DVMD

FIG 5 DVMD test report

FIG 6 Data rate of all programs in transportstream determined by DVMD


Menu-guided operation and display

The LCD of DVMD is used to operate itand display information. A TV monitorcan also be used for this purpose viathe OSD function (onscreen display).The OSD function displays the colouredmenus with the desired transparency inthe decoded picture (FIG 1). This givesa clear display of detailed measure-ment results. The following test menusare available:• joint display of error counters for all

monitored parameters (FIG 4),• preparation of a detailed test report

(FIG 5),• display of all programs in the trans-

port stream with information on program structure, data rates andscrambling (FIG 6),

• list of all elementary streams in a pro-gram plus associated data rates.

LEDs on the front panel of DVMD directly display each of the first-prioritytests (TS_sync, Sync_byte, PAT, Continu-ity_count, PMT [3]) and the main tests in the second priority group (Trans-port_error, CRC). All other tests in thesecond and the third priority groups areindicated by a single LED.

User-friendly remote control

DVMD offers full remote control. All settings and queries can be made via a serial interface. In addition, datacontained in the transport stream may be read and analyzed further.This applies to data sections with syntax errors (trigger on error) as wellas to filtered data components (egpackets of a substream or packets withadaptation field).

DVMD offers more than just access to a new TV measurement technique. It provides comprehensive informationon structure and syntax and allows detailed monitoring and analysis of the protocols used for any MPEG2 mul-tiplex data stream.

Michael Fischbacher; Harald Weigold

REFERENCES

[1] ISO/IEC 13818: Generic Coding of MovingPictures and Associated Audio Information

[2] DVB Document A010: Interfaces for CATV/SMATV Headends and Similar ProfessionalEquipment

[3] DVB-TM 1601: Measurement Guidelines forDVB Systems

[4] DVB-TM 1341: Common Interface Specifi-cations for Conditional Access and other Digital Video Broadcasting Decoder Appli-cations

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Condensed data of MPEG2 Generator DVG and MPEG2 Measurement Decoder DVMD

DVG

Output signals transport stream to ISO/IEC 13818-1

Length of transport stream packets 188/204 bytes (settable)

Data rate of transport stream 0.6 to 54 Mbit/s (settable)

Total data rate of elementary streams up to 15 Mbit/s

Total data quantity of elementary streams 100 Mbits

Stored signals approx. 20 transport streams (MP@ML),moving picture sequences, test patterns,test tones, teletext

Signal outputs 1 x TS parallel (to DVB-A010),2 x TS ASI (to DBV-A010)

Interfaces ports for PC peripherals

DVMD

Input signals transport stream to ISO/IEC 13818-1

Length of transport stream packets 188/204 bytes

Data rates of transport stream 0.6 to 54 Mbit/s

Signal inputs 1 x TS parallel (to DVB-A010),2 x TS ASI (to DVB-A010)

Tests to DVB-TM 1601 1st priority (Ts_sync, Sync_byte, PAT, Continuity_count, PMT, PID)2nd priority (Transport_error, CRC, PCR, PCR_accuracy, PTS, CAT)3rd priority (NIT, SI_repetition, unreferenced_PID, SDT, EIT, RST, TDT)

Other tests trigger on error, data rates of transportstream or substreams

Decoder outputsVideo 2 x CCVS, 1 x Y/C, 1 x ITU-R 601Audio 2 x analog audio L/R (LEMO),

1 x AES/EBU

Interfaces RS-232-C



The international specification for theDAB (digital audio broadcasting)system (ETS300401), which was pub-lished in 1994, was prepared by renowned research institutes, soundbroadcasting corporations and indus-trial companies as part of the Euro-pean project EUREKA 147. From thevery beginning Rohde & Schwarzplayed a decisive role in this work [1].

The L-band Transmitters NL5010(100 W) and NL5020 (200 W) weredeveloped on this basis and now com-plete the line of Rohde & Schwarz DABtransmitters. Thanks to their design,quality, and operating philosophy they fit perfectly into the range of well-proven Rohde & Schwarz transmitters[2]. The main components of the transmitters are COFDM ModulatorMCM01 [3], Exciter SD100A2, Ampli-fier VL5010, primary-switched PowerSupply IN916, power distribution anda high-pressure fan, which are all de-signed as plug-in units and accom-modated in a transmitter rack (FIG 1).

Since a new type of amplifier is used in the transmitters, the output bandpassfilter for limiting out-of-band transmis-sions may also be integrated in therack. This was not possible with pre-vious transmitter models. There is alsoample space to accommodate a GPSfrequency standard (option).

Function

Depending on the type of ETI (ensembletransport interface) to the transmittersite, the signal from the satellite de-modulator or from another source is fedto COFDM Modulator MCM01 (FIG 2),which π/4 DQPSK-modulates the data onto carriers, the number of whichis determined by the selected DABmode. This baseband DAB signal withspectrum width of approx. 1.5 MHzand center frequency of 2.048 MHz isapplied to Exciter SD100A2. Aftermixing to a fixed IF (38.902 MHz) thesignal is amplitude- and phase-equa-lized and then finally converted to anL-band frequency in the range 1452 to1492 MHz (setting increment 25 Hz).The RF signal is then amplified in theexciter and routed to the transmitteroutput stage, directly in the 100-W

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100/200-W Solid-State DAB Transmitter NL5010/5020

Terrestrial broadcasting of digital audio in L bandThe 100/200-W Solid-State L-Band DAB Transmitter NL5010/5020 completes therange of Rohde & Schwarz DAB transmitters which cover all DAB frequencies. The new audio broadcast transmitter operates in the frequency range 1452 to1492 MHz and fully complies with the requirements made on a modern DABtransmitter.

FIG 1 100-W Solid-State DAB TransmitterNL5010. 200-W model contains second amplifiermodule in transmitter rack. This type of transmitterhas already been in use for more than one year atWendelstein as part of world’s largest DABnetwork. Photo 42 530


transmitter or via a power splitter in the200-W transmitter.

Transmitter operation (eg on/off, pow-er and frequency setting, deemphasis)is menu-guided and performed from theexciter using a backlit LCD and the key-pad. The exciter also displays the statusof all relevant transmitter functions andis used to monitor and control the trans-mitter. A remote-control unit includesfloating contacts for transmitter switch-on and switch-off as well as for monitor-ing the operating status of the wholetransmitter.

transmitter (∆f/f = ±1 x 10–9) must beobtained from a highly accurate GPSfrequency standard. This standardsupplies a 10-MHz pilot frequency andmakes the reference frequency avail-able to any site within the network. Adirectional coupler at the antennaoutput feeds the RF test output and theforward and reflected power that iscoupled out and displayed on theexciter.

The primary-switched power supplywith self-engaging connectors providesall the voltages needed by the DABtransmitter. The power distributor con-tains a contactor for switching on thehigh-pressure fan and a phase monitorwhich sends the “power supplypresent” message for the transmitter’sthree-phase power supply. The high-

swing so that intermodulation productsinside and outside the useful frequencyrange are minimized.

To meet these requirements Rohde &Schwarz developed the solid-stateL-band DAB Transmitter AmplifierVL5010. Even without an output band-pass filter, the compensated amplifierhas intermodulation suppression of 30 dB. The RF signal from the exciter isrouted via a preamplifier, a power split-ter and two further amplifier stageseach with four parallel push-pull ampli-fiers (FIG 3). At the output of these par-allel circuits, a proportion of the poweris coupled out by a directional couplerand fed to the gain control in the pre-amplifier. If a transistor in a particularmodule fails, protection circuits in themodule prevent a power increase in the

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pressure fan provides adequate cool-ing for the power supply and amplifier.All components are designed so that afairly small, coarse air filter is sufficient.

DAB transmitter amplifier

The DAB signal is a multicarrier signalwith its information in the relative phaseof the π/4 DQPSK-modulated carriers.With certain information it is possiblefor many carriers to have the samephase. Carrier amplitude reinforcementoccurs and, in critical cases, an excep-tionally high input signal is applied tothe output amplifier for a short period.The output amplifier must, therefore, behighly linear over the entire voltage

If the DAB transmitter is to be part of a single-frequency network (SFN), therequired frequency stability of each

FIG 2 Block diagram of 100/200-W L-band transmitter

FIG 3Amplifier of Solid-

State DAB TransmitterNL5010

ETI signal Antenna output 100/200 W

Output bandpass

filter

GPS frequency standard

COFDM modulator Exciter

Switch-mode power supply

Remote-control unit

Output stage

Output directional coupler

Measured power

DAB signal L Band

Switch-mode power supplyPilot frequency

10 MHz

GPS antenna

Main switch

DAB signal 2.048 MHz

Control voltage

RF signal

from exciter

RF signal to directional coupler

3-dB couplerPower splitter

Feedback preamplifier

Directional coupler


other modules. This ensures high reli-ability and a long service life for thewhole amplifier. If the temperature atthe specially designed aluminium heat-sink is too high, a temperature sensor in each of the two parallel amplifiermodules can switch off the carrier. Acirculator at the output of each 100-Wmodule protects the transistors in thetransmitter amplifier if there is excessivemismatch.

Practical applications

In July 1995 the participants in theT-DAB planning meeting in Wiesbadenfinalized frequency and band allo-cations for terrestrial DAB. All DABtransmitters from Rohde & Schwarz operate in the approved frequencyranges of 174 to 240 MHz and 1452to 1492 MHz. However, transmittersare also available for the ranges 47 to68 MHz and 87.5 to 108 MHz to cover the whole frequency range usedby DAB transmitters. Thanks to a four-section output bandpass filter, the newDAB solid-state transmitter has no prob-lems with the tolerance mask specifiedfor its frequency range (FIG 4). Thismask stipulates the maximum level foremissions outside the frequency bandoccupied by the carriers.

In autumn 1995, the first EuropeanDAB pilot project was launched in Ba-varia [4]. Since then Rohde & Schwarztransmitters have been demonstratingtheir excellent quality and flexibility asstand-alones or as part of single-fre-quency networks far beyond the bor-ders of Bavaria and Germany. Thanksto the company’s high level of expertisein the field of DAB, Rohde & Schwarzhas participated as a system and com-

ponent supplier in all DAB projects todate (ARD pilot project, Deutsche Tele-kom, Australia, Switzerland, Sweden,etc) and so has made a major contribu-tion to their success.

Rainer Steen; Johannes Steffens

REFERENCES

[1] Mayr, J.: DSR and DAB – Digital sound broad-casting today and tomorrow. News fromRohde & Schwarz (1994) No. 145, pp44 – 45

[2] Steen, R.: 250-W Solid-State DAB TransmitterSM225D1 – Terrestrial sound transmitter fordigital audio broadcasting. News from Rohde& Schwarz (1995) No. 148, pp 29 – 31

[3] Heinemann, C.: COFDM Modulator MCM01– Channel coding and modulation for digitalaudio broadcasting. News from Rohde &Schwarz (1995) No. 148, pp 26 – 28

[4] Kalthoff, W.: Bavaria has started into DABfuture. News from Rohde & Schwarz (1995)No. 149, pp 48 – 49

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Condensed data of 100/200-W Solid-State DAB Transmitter NL5010/5020Frequency range L band, 1452 to 1492 MHz

Input signal ETI version 4.0

Output signal to ETS300401

RF output power 100 W (NL5010)/200 W (NL5020)

Intermodulation suppression(fo > ±977 kHz) >30 dB

Max. frequency errorwithout/with GPS unit 1 x 10–7/1 x 10–9

Line voltage 3 x 400 V ±15%

Power consumption 1.3/2.3 kW

Cooling air intake approx. 7/13 m3/min

Dimensions (W x H x D) 583 mm x 2026 mm x 1000 mm

Weight approx. 275/310 kg


FIG 4 Specificationfor DAB emissions inL band (measurementbandwidth 4 kHz)

0.770.97

Critical maskNon-critical mask

0

-10

-20

-30

-40

-50

-60

-70

-80

-90

Leve

l rat

io o

f in-

band

to o

ut-o

f-ban

d po

wer

Offset to center frequency

0 0.5 1 1.5 2 2.5 MHz 31.75

dB


High-grade test equipment is indispens-able for putting TV transmitters into ser-vice and maintaining them to ensurethat the highest transmission quality can always be obtained. In addition toITS systems for on-air monitoring of TVtransmitters, Rohde & Schwarz now of-fers TV Transmitter Test System TS6140(FIG 1), based on Test System UCMF[1], for extensive, full-field transmissioncharacteristic measurements off air. It is a reliable and easy to operate testsystem that has full-featured manual operation but also computer-aided test programs to simplify operation andprevent incorrect measurements.

Method of operation and design

TV Transmitter Test System TS6140 hasall the features required for measuringthe transmission characteristics of a TVtransmitter to German standard specifi-cations [2; 3] (FIG 2). In Signal SelectorMFA703 the connections for the videoand audio signals to and from the TVtransmitter are made, the measuring instruments are configured and the RFand IF links between the test system andthe transmitter are set up, depending onthe measurement task. It also compen-sates for frequency response of the testcables. The TV transmitter is connectedby means of cabling which can also be used for alternative DUTs (eg test de-modulator or relay receiver). Inputs andoutputs provided for video and audiosignals on the front panel are used fortesting individual units or PC boards,eg for repairs. These connections canalso be reconfigured with the signal selector. All units are connected to Process Controller PSM7 via interfaces

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TV Transmitter Test System TS6140

Guarantee of high signal qualityin TV transmitter networksDoes a TV transmitter comply with standard specifications? Is it possible to meas-ure individual parameters during servicing? Can operating errors be avoidedduring servicing? These are questions which a TV network operator may ask.Rohde & Schwarz answers: no problem with TV Transmitter Test System TS6140,the fourth generation of R&S test systems for television.

FIG 1 Mobile version of TVTransmitter Test System TS6140for comprehensive off-air vision and sound measurementsPhoto 42 486


(IEC/IEEE bus, serial interfaces) to control the test and output the results.The flexible system concept means thatcustomer-specific tasks can be accom-modated.

Characteristics and applicationsTV Transmitter Test System TS6140 ismenu-controlled via the process control-ler. The operating program was devel-oped as an application under MicrosoftWindows; its graphics user interfaceprovides a powerful user-friendly oper-ating environment. TS6140 can, ofcourse, be manually operated to per-form one-shot measurements. Signal-path switching is carried out from Operating Panel MFA801 or via theprocess controller’s graphics user inter-face. The signal paths are displayedclearly as symbols and block diagrams.Connection is made immediately whenthe path is clicked with a mouse. Themeasuring instruments are set from thefront panel and test results are evaluat-ed via the front-panel display of eachinstrument.

The operator can also use computer-aided measurement for service proce-

dures. He selects the measurement itemfrom a menu of ready-to-run measure-ments and performs it interactivelyhelped by the computer. The appropri-ate parameters are set via the graphicsuser interface (FIG 3). Depending onthe task, the computer can handle device settings, signal path switchingand choose a display mode for the testresults.

The results of each measurement arestored in a database on harddisk andcan be exported to a floppy disk. Com-ments can be added to each measure-ment and printed out at a later date.

TV Transmitter Test System TS6140 canalso support acceptance tests or beused to document the condition ofequipment before and after repair workperformed with automatic measure-

ments. The operator selects the meas-urements to be carried out from a tableand specifies how the data are to behandled (storage, printing). After con-firmation of the settings, the measure-ments are run automatically in the se-lected order. The parameters (testpoint,vision signal, etc) can also be config-ured separately. The automatic meas-urements handle all aspects of accep-tance testing for TV transmitters coveredin standard specifications. The com-prehensive help function, specially de-signed for TS6140, can be called fromany mode and so, in effect, is an onlineoperating manual.

Special test facilities

TS6140 provides a number of newfeatures that earlier generations of TVtransmitter test systems did not have:

• Measurements can be made not on-ly on the TV transmitter but also onthe test demodulator, relay receiver,transposer and VF amplifier.

• Vision-Sound Modulator CT200-VStogether with Sound-2 Coder-Mod-ulator CT200-S2 and UpconverterCT200-UP generates the required IF and RF test signals.

• Power Meter NRVS and Peak PowerSensor NRVS-Z31 accurately andrapidly measure the maximum avail-able envelope power of periodicallypulsed RF signals into 50 Ω and areused for direct measurement of peakenvelope power. Coupling and linelosses are taken into account andcorrected.

• Spectrum Analyzer FSEA20 [4] withits tracking generator provides theanalyzer mode and can also per-form frequency measurements. Thefrequency counter can be synchron-ized to an external reference andresolution set down to 0.1 Hz. Theanalyzer resolution bandwidth canbe selected in 1, 2, 3, 5 steps from10 Hz to 10 MHz, the dynamicrange is 95 dB. The RF and VF am-plitude-frequency responses can bemeasured with FSEA20 and the mixer in MFA703.

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FIG 2 Block diagram of TV Transmitter Test System TS6140

FIG 3 Operating program for one-shot meas-urement

Spectrum Analyzer FSEA20

Video Measurement System VSA

CCVS Generator

SFF

CATV Head- end Equip-

ment CT200

TV Demod- ulator AMFS

Audio Analyzer

UPD

Power Meter NRVS

Process Controller

PSM7

Signal Selector MFA703


• Audio Analyzer UPD [5] measuresdual-sound operating data. Theswitchable weighting filters allowmeasurement of weighted and un-weighted S/N ratios to DIN/CCIR,the tracking bandpass is used formeasuring stereo and channel cross-talk and the distortion meter for de-termining total harmonic distortionand the distortion for single harmon-ics.

• Video Measurement System VSA [6]is used to measure signals in the time domain and to determine groupdelay. The video and FFT analyzerof VSA simultaneously computes upto 150 parameters from the input signal. Analysis of the sin x/x signalfrequency spectrum calculated withFFT gives the group delay curve.

Westdeutscher Rundfunk was the firsttransmitter network operator to use themodern TV Transmitter Test SystemTS6140. It has been in operation forseveral months at three sites and thissystem will soon be installed in six other transmitter stations and a test laboratory.

Walter Deschler; Gerhard Strauss

REFERENCES

[1] Deschler, W.: Television Test System UCMF– service for vision and sound. News from Rohde & Schwarz (1992) No. 138, pp 18–20

[2] DBP/ARD: Standard Specifications No.5/1.0, parts 1 and 2

[3] DBP/ARD: Standard Specifications No.5/2.1, January 1992

[4] Wolf, J.: Spectrum Analyzer FSEA/FSEB –New dimensions in spectral analysis. Newsfrom Rohde & Schwarz (1995) No. 148,pp 4–8

[5] Kernchen, W.: Audio Analyzer UPD gener-ates and measures analog and digital au-dio signals. News from Rohde & Schwarz(1992) No. 139, pp 13 –15

[6] Bichlmaier, T.; Finkenzeller, R.: Video Meas-urement System VSA – Four TV measuringinstruments plus controller in one compactunit. News from Rohde & Schwarz (1995)No. 147, pp 18–21

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Test parameters covered by TV Transmitter Test System TS6140Measurements on vision transmitters transmitting power, vision-sound ratio,

frequency, spurious emissions, level,amplitude-frequency response, VF group delay, tilt, settling time, luminance nonlinearity, chrominancenonlinearity, difference-frequency distortion, phase deviation of vision carrier, intermodulation, unwanted modulation, intercarrier interference ratio

Measurements on sound transmitters frequency deviation (levelling), differential deviation, amplitude-frequency response, preemphasis, stereo and channel crosstalk, THD and difference-frequency distortion, unwanted FM modulation, polarity


ReferenceEMC system solutions:We watch the rule

This was the motto of a comprehensive PR cam-paign Siemens Matsushita Components started in the leadup to 1 January 1996, the date as ofwhich electronic products irrevocably had to comply with German EMC legislation. The rangeof EMC test equipment, accessories and softwarepackages has become larger, and small- and medium-sized companies now have the possibil-ity of performing at least some EMC measure-ments using their own personnel and equipment.The focus in one of the ads by which Siemens Matsushita Components presented its EMC prod-uct line is an EMC test assembly from Rohde &Schwarz (photo). This assembly comprises a test antenna, a PC with test software (left), a test receiver (center) as well as a signal generator, an artificial mains network and a power amplifier(right, from bottom).

Rohde & Schwarz is the pacemaker and world-market leader in EMC compliance test engineer-ing. Participation in international standardizationbodies ensures that hardware and software are al-ways in conformance with the relevant standards. The company’s com-petence and efficiencyis also underscored bythe fact that Europe’slargest EMC test cen-ter in Greding was de-signed, equipped andhanded over turnkeyby Rohde & Schwarzand that practically allrenowned firms in theautomobile and elec-tronics industry rely

upon support and products from Rohde & Schwarz.Rohde & Schwarz offers test receivers, spectrum an-alyzers, signal generators, amplifiers and antennasfor measuring interference and electromagnetic sus-ceptibility of machines, vehicles and the like. Sö


FIG 1 DF and monitoring vehicle with VHF-UHFDirection Finder DDF190. With its upper fre-quency of 3 GHz, DDF190 can also detect sources of interference affecting new radio ser-vices (eg GSM, PCN, PCS, WLL and GPS).

Photo 42 572

Digital signal processing coupled withinnovative RF technology has set newstandards in many fields and directionfinding is one of them. DDF190, a fullyremote-controlled DF add-on for com-mercial receivers with an unregulated10.7-Hz or 21.4-MHz IF output followson from the fast Scanning DirectionFinder DDF0xS [1] and Monitoring Direction Finder DDF0xM [2]. ESMCand ESN from the Rohde & Schwarz receiver program are ideal for use with DDF190, which is a very cost-effective way of adding an extremelybroadband direction finder to high-quality measuring and monitoringsystems.

DDF190’s design meets the recommen-dations in the ITU Spectrum MonitoringHandbook [3]. The wide frequencyrange from 20 to 3000 MHz and highsystem accuracy make DDF190 idealfor civil radiomonitoring tasks. Thanksto its compact design it can be used formobile as well as stationary applica-tions (FIG 1). Since DDF190 is alsosystem-compatible, it can be used as astand-alone unit or be networked fora variety of system applications. Thewhole frequency range is covered withjust two antennas. Since only one co-axial cable and control cable are re-quired to connect up DF Unit EBD190,installation is simple and low-cost. Thedirection finder can, of course, be powered from a battery or the AC sup-ply. In both cases the DF unit providesthe supply voltage for the active anten-

nas. When used for stationary applica-tions, the antennas can be located up to95 m from the DF unit using the stan-dard cable sets. For cables longer than40 m an additional power supply unitis provided.

Direction Finder DDF190 operates as a correlative interferometer and canhandle all types of modulation. The direction finding procedure makes useof digital signal processing. The phasedifferences between the antenna volt-ages generated by the signal receivedby the antennas are compared with reference values and then checked formaximum correlation. The advantageof this DF method is that, because antenna elements do not need to begrouped into subarrays, wide-apertureDF antennas can be used coveringlarge frequency ranges with a minimumnumber of antenna elements.

Operation

DF Unit EBD 190 is operated using aclearly laid-out front panel keypad and a large LCD (FIG 3). All functionsrequired during operation are under di-rect key control. The receiver is operat-ed separately, but the interfaces for an-tenna range selection are supported.Since direction finding is performed bysequential scanning of the DF elements,and only one receiver is used, switch-ing noise is produced in the AF signalof the receiver. To eliminate this noisewhen aural monitoring is being per-formed, scanning and so direction find-ing may be switched off. Selectable av-eraging times (0.1 to 5 s) and matchedfiltering in DDF 190 (1 to 100 kHz) con-siderably improve bearing accuracy –particularly in the case of noisy signalsor signals with interference.

Three operating modes and two dis-play modes optimize direction findingfor various applications.

In normal mode the DF process is con-trolled by a selectable squelch thresh-old which is compared with the current-ly received, relative IF level. It is best to

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VHF-UHF Direction Finder DDF190

Digital direction findingfrom 20 to 3000 MHz to ITU guidelinesDDF190, the youngest member of the new digital DF family, has now beenlaunched on the market. This compact DF add-on for VHF-UHF receivers is available at an extremely favourable price. It operates on the correlation principle and is mainly used for locating sources of interference and unauthor-ized emitters.


use this mode for monitoring radio networks or simplex communication.Bearings of short-duration signals (min-imum 50 ms) can also be taken. As theselected averaging is cancelled at the end of a signal, the bearing displayfollows the changing directions of incidence without any delay.

In continuous mode direction finding isperformed continuously. With slidingaveraging, the display is updated every 0.5 s. This means that directionfinding can be performed on weak signals or signals with a very largebandwidth.

The gate mode is used for bearings onkeyed transmitters as the squelch thresh-old is also activated but the averaging

memory is not cleared if the signal isbelow the threshold. Integration overmany pulses is therefore possible.

The DF display comprises a three-digitnumber and a radius for indicating direction. The DF quality, derived fromthe correlation function, is displayed

with each DF value. For stationary ap-plications, a compass with north adjust-ment is used as a reference and the vehicle axis for mobile applications.The latter is crucial when the vehicle isbeing used for homing. In this case acompass is also used to continuously indicate where north is with respect tothe vehicle. Vector direction findingwith QDM as used in air traffic controlcan also be selected.

In each of these modes DF values canalso be displayed as a histogram inaddition to the display mode alreadyreferred to. This is very useful for ana-lyzing communication networks: all DFvalues obtained since this display modewas activated are displayed as rays,the length of each ray being a measureof the frequency of occurrence of thebearing angle it represents. Results canalso be displayed and printed out as lists. Postprocessing functions likesmoothing, determination of local max-ima and sorting support histogramanalysis.

On power up of the direction finder, thesystem environment (antennas, classof receiver, compass) is automaticallydetermined. A realtime clock outputs atime marker for each bearing taken.This facilitates bearing/emitter assign-ment in networked DF and radioloca-tion systems.

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FIG 2 DDF190 upgrades VHF-UHF receivers totop-end DF system – with accuracy and sensitivityabove 1 GHz unrivalled by any other compactunit. Photo 42 571/1

FIG 3 Front view of

DF Unit EBD190Photo 42 473


Antennas

The range 20 to 1300 MHz is coveredby Antenna ADD190. Its small diame-ter of only 1 m and the uncriticality ofpolarization make the antenna ideal formobile applications although it also hasconsiderable advantages in stationaryuse. Thanks to its small size, it is unob-trusive, protected as standard againstdirect lightning strikes and can with-stand wind speeds of 200 km/h.

Antenna ADD071 is provided for theUHF range 1.3 to 3 GHz. Designed as a circular array of dipoles in front of a reflector, ADD071 may be fitted on the same mast as ADD190 (FIG 4).This combination is already availableas standard.

An electronic compass add-on may be fixed to the antennas for automaticdirection finding referred to north.

System compatibility

DF Unit EBD190 provides remote con-trol via a serial RS-232-C interface. Remote control (virtual control panel) is identical to front-panel operation. The DF unit also provides an RS-422/RS-485 and a TTL parallel interface for the connected receiver. Character

sequences for receiver control arepassed on by the DF unit. Compactcommands and configurable messageformats reduce the required commu-nication capacity to a minimum. Twomodes using a minimum number ofmessages are provided in addition tothe three operating modes: timed singleand repetitive DF. An external controlinput is provided for a radio modem;this does not affect direction finding in any way (internal transmitter sup-pression).

To create larger systems with DF sta-tions at any location, Rohde & Schwarzoffers comprehensive solutions into

which DDF190 can be directly integrat-ed. Radiomonitoring System TS9965[4] provides fully automatic monitoring,measurements and analysis to CCIRand ITU recommendations. In the DFmeasurement mode, results from sever-al DF stations can be handled andmarked on a digitized map. Within thissystem, DDF190 may be connected toreceivers with IEC/IEEE-bus control inunmanned stations. Channel and fre-quency scans are also supported. TheRadiolocation System RAMON-locate[5] was designed to accommodate theDDF190/ESMC combination.

Franz Demmel; Raimund Wille

REFERENCES

[1] Bott, R.: Digital Direction Finder DDF – Mod-ern scanning direction finding from 0.5 to1300 MHz. News from Rohde & Schwarz(1994) No. 146, pp 26–28

[2] Demmel, F.; Unselt, U.; Schmengler, E.: Digi-tal Monitoring Direction Finders DDF0xM –State-of-the-art monitoring direction findingfrom HF to UHF. News from Rohde &Schwarz (1996) No. 150, pp 22–24

[3] International Telecommunication Union:Spectrum Monitoring Handbook (1995)

[4] Pfitzner, J.: Radiomonitoring System TS9965– Complete coverage up to 18 GHz. News from Rohde & Schwarz (1994) No.146, pp 22–25

[5] Ehrichs, R.; Holland, C.; Klenner, G.: Radio-monitoring System RAMON – Customizedradiomonitoring from VLF through SHF.News from Rohde & Schwarz (1996) No. 151, pp 19–21

Articles

Condensed data of VHF-UHF Direction Finder DDF190Frequency range VHF/UHF (20 to 1300 MHz)(depending on receiver and DF antenna) UHF (1.3 to 3 GHz)

DF error 2° rms (30 to 80 MHz)1° rms (80 to 1300 MHz)2° rms (1.3 to 2.7 GHz)

DF sensitivity frequency-dependentVHF/UHF 1.5 to 10 µV/mUHF 3 to 10 µV/m

Minimum signal duration approx. 50 ms

Bandwidths 1/2.5/8/25/100 kHz


FIG 4 Antennas ADD190(top) and ADD071on common mastPhoto 42 477/1


Apart from an RF signal of high spectralpurity and precisely adjustable outputpower, signal generators for EMCmeasurements require top-quality AMand pulse modulation, spike-freefrequency and level sweeps and lastbut not least a mature operating con-cept permitting automatic measurementsequences to be performed with orwithout an external controller. Themicrowave generators from the SMPfamily set the standards – as do allother signal generators from Rohde &Schwarz. Four models and a compre-hensive range of options are availablefrom which the user may choose theequipment he needs – tailored to hisspecific requirements – at an excellentand unrivalled price/performance ratio[1 to 3].

The term electromagnetic compatibility(EMC) is very apt: if people are com-patible they can work together easilyand effectively without anyone disturb-ing anyone else, and the same appliesto electrical devices. Certain groundrules must be observed in any partner-ship and this is why EMC standardsand suitable measuring instrumentswere developed at a very early stage.However, the frequency range did notgo beyond 1 GHz as this was all thatwas required for all the main activitiesof modern radiocommunication. Therange beyond 1 GHz was generally reserved for military and scientific applications.

The need for EMC testing has alwaysbeen appreciated by forward-lookingmanufacturers of top-quality electronicdevices and systems. The end of thetransition period for the CE mark at thebeginning of this year would not havebeen a reason to implement any majorchanges as EMC awareness was al-ready considered good practice. TheEMC test equipment used today derivesfrom equipment for military applica-

tions, where sensitive receivers, power-ful transmitters and noisy engines havealways had to operate in close proxim-ity without interfering with one another.Compatibility principles were, there-fore, defined and appropriate testequipment developed. Adapted topresent-day requirements, these princi-ples are now the basis of current nation-al and international EMC regulations.

As said already, mature standards andtest specifications are currently avail-able for civil and military applicationsin the range up to 1 GHz. Militarystandards still apply to higher fre-quencies, although lately more andmore civil applications are transferringto this range. Examples can be found insatellite communications as well as inautomobile and aeronautical engi-neering. It can be assumed, therefore,that standards for EMC tests will beextended to 40 GHz in the near future.New top-class technology at an afford-able price will obviously be required

Application notes

EMC measurements up to 40 GHz with MicrowaveSignal Generator SMP

FIG 1 Signal Generator SMP and GTEM (giga-hertz transverse electromagnetic) cell – an up-to-date combination for susceptibility measurements

Photo 42 574

FIG 2 Measurementof immunity to radiatedinterference from 1 to40 GHz using SignalGenerator SMP (to MIL-STD-462D). SignalGenerator SMP04 (10 MHz to 40 GHz)is used as stimulator,EMI Test Receiver ESMIwith Harmonic MixerFS-Z40 for display purposes and field-strength measurements.

Power amplifier

Simulation and display

Signal Generator

SMP04

Field-strength meter

DUT

Artificial-mains network

Antenna

Shielded chamber

E field sensor

Boundaries of test setup


and is already available in the form ofgenerator family SMP (FIG 1) fromRohde & Schwarz with models from 10 MHz/2 GHz to 20, 27 and 40 GHz. The table in the blue box gives a selection of current military and civil EMC standards covering 1 to40 GHz.

A glance at the standards shows themain fields of application for micro-wave signal generators. First, there aremeasurements of immunity to radi-ated interference – also known as sus-ceptibility measurements. In this casethe signal generator usually drives apower amplifier with an appropriate

bandwidth connected to an antennaemitting the signals for irradiating theDUT (FIG 2). Depending on the require-ments, the DUT’s functions should notbe impaired at all or only within certaindefined limits. In particular, there maybe DUT resonances at the high-frequen-cy end of the microwave band: smallslits in the housing or short line struc-tures in circuits or on PCBs may act ashigh-Q resonators and cause total fail-ure in an extremely narrow frequencyrange. Thanks to SMP’s digital sweepsuch resonance points can be rapidlyand reliably detected, the smallest set-table increment being 0.1 Hz. The ex-cellent frequency stability also ensuresthat measurements can be reproduced.Any DUT malfunction can be found anddemonstrated at a later date. Anotherimportant advantage of the SMP sweepis that there are no level spikes. Levelspikes may destroy any power ampli-

fier down-stream or even the DUT and will certainly cause measurementerrors.

Another main application of micro-wave signal generators is the calibra-tion of test setups, as shown in FIG 3.Prior to the actual measurement, the signal generator is used to calibrate the level display of the test receiver. Obviously, the accuracy and stability ofthe generator level have to meet strin-gent requirements. Thanks to an over-designed ALC system and careful instru-ment calibration in the factory, this is noproblem for generators from the SMPfamily. The test receiver used in test setups like that shown in FIG 3 can also be calibrated by applying the generator signal to the receiver via an antenna and not via a cable [2]. Thismeans that the transfer characteristicsof the receiving antenna are also takeninto account.

Normally, frequency drifts in RF cables,power amplifiers and the antenna ofthe test setup cause considerable levelerrors. This cannot be avoided in spiteof the excellent level accuracy of SMP(typical error 0.1 dB). Fortunately, SMPdoes have a number of functions forfrequency response correction:

Application notes

Standard Designation Description Microwave range Application

MIL-STD-461D/462D Radiated Emissions, Measurement of harmonics 1 to 40 GHz Military (USA)RES103 Antenna Spurious and and spurious emissions

Harmonic Outputs from antennas

MIL-STD-461D/462D Radiated Susceptibility, Measurement of immunity to 1 to 40 GHz Military (USA)RES103 Electric Fields radiated RFI (electric field)

DEF STAN 59-41 Radiated Susceptibility Measurement of immunity 0.79 to 18 GHz Military (UK)(PART 3), DRS03 to radiated RFI

VG 95 370/VG 95 373, Messverfahren für Störsicherheits- Measurement of immunity 1 to 40 GHz Military (Germany)Teil 13, abstände gegenüber systemeigenen to radiated RFIMessverfahren SF 04 G Feldstärken

SAEJ1113 Part 21 Semi-anechoic Chamber Measurement of immunity 0.03 to 18 GHz Vehicle test (USA)to radiated RFI

ISO 11451-2/ Road vehicles – Electrical disturbances Measurement of immunity 0.2 to 18 GHz Vehicle test ISO 11452-2 by narrowband radiated electromagnetic to radiated RFI (international)

energy – vehicle test methods – Part 2: Off-vehicle radiation sources

EN 50083-2 Cabled distribution systems for television Measurement of radiated 1 to 25 GHz Telecommunications, and sound signals – Part 2: interference TV and sound Electromagnetic compatibility (substitution method) broadcasting (Europe)for equipment

Selection of currently valid military and civil EMC standards for the microwave range

FIG 3 Measurement of radiated harmonics andspurious from 1 to 40 GHz to MIL-STD-462D usingSignal Generator SMP and EMI Test Receiver ESMI

Bandstop or

highpass filter

Power monitor

Signal Generator

SMP04

DUT (transmitter)

Transmitting antenna

Bandpass filter

EMI Test Receiver ESMI +

Harmonic Mixer FS-Z40Receiving

antenna

Signal path for measurement

Signal path for system check


• user correction for a user-defined RFfrequency response,

• memory sequence, a programmablesequence of complete front-panel setups,

• list mode, a programmable se-quence of up to 2003 frequen-cy/level pairs,

• and, last but not least, external levelcontrol using an external power me-ter [4].

When SMP is operated manually, iewithout an external controller, it is bestto use the user correction function tocorrect the overall frequency response.If a Power Meter NRVS or NRVD isavailable, the required correction values can be determined automati-cally by means of a keystroke. Pro-

grammers of automatic test systems pre-fer direct frequency response correctionvia IEC/IEEE bus using the controller. In this case, level control is performedby SMP’s ALC, giving resolution of0.01 dB. The actual value is deter-mined by means of a power meter withdirectional coupler at the antenna inputor via a field-strength sensor near theDUT.

The above examples clearly show thatSMP, a powerful, future-oriented and favourably priced instrument from amanufacturer with decades of experi-ence in all fields of EMC measure-ments, is the right solution to any EMC measurement problem between10 MHz and 40 GHz.

Wilhelm Kraemer

REFERENCES

[1] Kraemer, W.: Signal Generator SMP – Themicrowave generator for stringent require-ments. News from Rohde & Schwarz (1994)No. 144, pp 11 – 14

[2] Kraemer, W.: Signal Generators SMP03 andSMP04 – Powerful microwave generators upto 40 GHz. News from Rohde & Schwarz(1995) No. 147, pp 10 – 13

[3] Kraemer, W.: Microwave Generator SMP –top-class performance to customer’s benefit.News from Rohde & Schwarz (1995) No.151, pp 58 – 59

[4] Kraemer, W.: External, precision level controlfor microwave Signal Generator SMP. Newsfrom Rohde & Schwarz (1994) No. 144, p 14


Application notes

Test hint

DECT is not only used for classic applications such asdomestic cordless phones, but is also considered asolution for making the last step in the implemen-tation of new telecommunications networks. Thisapplication called WLL (wireless local loop) is atpresent being tested in various field trials. Otherthan with GSM, DECT frequencies are not allocatedto a specific operator but can be used by every type-approved DECT application. Consequently, theDECT frequency band has to be shared with DECTunits working in an uncoordinated manner. TheDECT standard allows for this by defining dynamicchannel selection (DCS) and associated handoverprocedures that switch over to other channels in caseof interference or sliding collisions to ensureinterruption-free communication.

The algorithm for dynamic channel selection has notbeen defined exactly. The solutions are manu-facturer-specific and not disclosed to the public. Thetraffic capacity specified for DECT, which is high incomparison with GSM, is based on theoreticalconsiderations assuming an optimum DCSalgorithm. To attain the specified value under real-world conditions, not only well-proven DCS

DECT Protocol Tester TS1220 (see News from Rohde & Schwarz No. 148) supports the operatorsof DECT WLL networks both in the assessment ofDCS algorithms and the optimal positioning of antennas. In the monitoring mode the system syn-chronizes itself to a user-defined DECT fixed partand logs all data packets exchanged with portableparts via the air interface without intervening withthe DECT network. On the basis of the data collect-ed, failed or successful handover and communica-tion attempts as well as occupied channels can be

detected. Thus the operator can draw conclusionsabout the strong and weak points of channel selec-tion algorithms.

In addition, the optional channel occupancy soft-ware informs the user about the receive levelsmeasured on all DECT channels (RSSI value) andabout the origin of the signals received. The signalsmight originate from coordinated or uncoordinatedDECT units and non-identifiable interference sources(FIG). The physical parameters of the DECT signalsand the identities exchanged are also indicated, sothe signals can very easily be allocated to sourcesinside or outside the network. Moreover, the optionallows antenna positions to be optimized using theRSSI values which are referred to the identities dis-played. TS1220 can either be installed in a vehiclefor mobile use and operated with its own height-adjustable antenna. Or it can be connected direct tothe antennas used in the network.

Marcus Gloger; Peter Riedel

Reader service card 152/12 for further infor-mation on TS1220

algorithms but also geographical conditions have tobe utilized optimally (eg by means of directionalantennas at the transmitter and receiver end).

Optimizing wireless local loop systems


The ear is an extremely sensitive organ.If healthy, it is capable of processingsounds with an extremely widedynamic range. Nevertheless, it caneasily be damaged by longterm ex-posure to, say, industrial noise or ex-cessive noise levels in discos or fromwalkmen. As the effect on hearing isoften only noticed later on, there is anincreasing number of young peoplewith hearing defects that have to becorrected with a hearing aid.

Hearing defects are caused by a widerange of impairments of the hearing ca-pacity, for example by frequency-dependent sensitivity losses in specificfrequency ranges or by a shifting of thecomplete sensitivity curve. Modernhearing aids must, therefore, be ca-pable of compensating for a variety ofdefects, and a precise determination oftheir electroacoustic characteristics isessential.

There are several national and inter-national standards (eg IEC 118 Parts 0to 12 and ANSI S3.22) that definemeasurements on hearing aids usingsinusoidal tones. Further standards (egANSI S3.42) defining measurementson hearing aids using a broadbandnoise signal are in preparation. For thelatter type of measurements, a signalwith precisely defined frequency distri-

bution and crest factor will be generat-ed and the correlation between the out-put signal of the hearing aid and the in-put signal determined. Manufacturers ofhearing aids, especially those supplyingthe US market, will shortly be obliged totest their products to these standards.With its Audio Analyzer UPD [1] andHigh-Speed Option UPD-B3, Rohde &Schwarz can already provide the testand measuring equipment required.

Special application programs forAudio Analyzers UPD and UPL [2]make it possible to perform measure-ments on hearing aids to IEC 118 andANSI S3.22. Measurements are per-formed in an acoustic test chamber,which may be an anechoic room or asmall test chamber with appropriatedamping. Commercial test micro-phones can be used, and the loud-speaker of the test chamber can bedriven directly by UPD (FIG 1) or UPL ifefficiency is sufficiently high. A couplerto IEC 126 or an ear simulator to IEC711 can be used for connecting themicrophone to the hearing aid. Nofurther equipment is required except fora printer if the user wishes to log results.

The application program runs underthe UPD or UPL universal sequence con-troller and is operated via softkeys orfunction keys on a keyboard. After

starting the program, the user canselect the standard according to whichmeasurements are to be performed, ieANSI S3.22 or IEC 118. Test settingsare stored separately for each standardand are recalled each time theprogram is started.

The measurement menu of the appli-cation program offers the followingchoice of settings and test functions:CONFIG, DUT, FRQ-RESP, IN-OUT,DIST, NOISE, ATTACK, CALIB.

Prior to initial measurement, the micro-phones and test chamber must be cali-brated using the CALIB menu item. Thecalibration data of the microphonesand the frequency response of the testchamber are stored and taken intoaccount automatically each time theprogram is restarted. After each cali-bration, the microphone data areadded to a file named MICRO.HST.This file can be analyzed to verify thestability of the microphone data.

The parameters for the test steps aredefined using the CONFIG menu item,for instance scaling for frequencyresponse measurements, broadband orselective measurements, etc. The dataare permanently stored and used in allsubsequent measurements.

Application notes

Measurements on hearing aids with Audio AnalyzersUPD and UPL

FIG 1 Audio Analyzer UPD – ideal for standardtests on hearing aids Photo 41 956

FIG 2 Frequency response of sound pressuresaturation level of hearing aid at maximum gain,and output sound level with input sound level of60 dB as reference


The DUT data are entered using theDUT menu item. These data are printedout with the result graphics.

One of the most important character-istics of a hearing aid is its frequency response: FRQ-RESP menu item. Tomeasure the response, the hearing aidis first of all set to maximum gain andthe output sound level measured at 90 dB sound pressure. This gives thesound pressure saturation curve. Next,the reference gain of the hearing aid isset and the frequency response meas-ured at 60 dB or 50 dB sound pressurelevel, depending on the type of hearingaid. The resulting curve is displayed inthe same diagram as the sound pres-sure saturation curve (FIG 2). On com-pletion of the measurement, the usercan rescale the Y axis as desired, dis-play the frequency response curve asthe acoustic gain curve and, in this dis-play mode, generate further curves, forinstance to determine the effect of fre-quency response controls by means ofa set of curves. Results can be output us-ing a HPGL printer, so providing docu-mentation that meets the standards forofficial product approval.

The acoustic transfer characteristic –IN-OUT menu item – of a hearing aid isneeded to correct sensitivity losses ofthe ear as a function of volume. Howthe transfer characteristic varies withfrequency can be determined byperforming measurements to obtain upto five traces (sound pressure level,gain or compression ratio) at selectablefrequencies (FIG 3).

A hearing aid should output the am-plified signal with as little distortion aspossible if the original sound is to bereproduced as faithfully as possible.Using the DIST menu item, distortion of the acoustic signal is measured at 70 dB sound pressure level over thewhole frequency range. The D2 andD3 distortion products are determinedand displayed as curves in a diagram.

The gain of the hearing aid is neededto restore the original sensitivity of the

attenuated by the test chamber if thismeasurement is to produce usefulresults.

A characteristic of hearing aids that isparticularly difficult to describe is theAGC response time. State-of-the-arthearing aids often have multistagecontrol circuits with different timeconstants. For example, individual gaincontrol or compression is applied tosyllables, so the response time must bemilliseconds. The ATTACK menu item isused to perform automatic measure-ments on the attack and release times ofhearing aids with AGC. The testconditions can be user-defined. Attackand release curves are displayed andevaluated by the program, and theresults output as numerical values. Forthe first time ever, a function has beenimplemented that provides an easyway of making measurements on anddocumenting the complex controlresponse of hearing aids from fractionsof milliseconds up to several seconds inone go.

Precise measurement of the electro-acoustic characteristics of a hearingaid is essential if the development,production and quality management ofthe product are to be improved. Thisinformation is also vital for the casenotes of patients whose hearing aidshave been adapted to compensate fora specific hearing problem. Like otherelectromedical equipment, hearingaids must undergo type testing beforethey can be sold. In Germany, suchtests are performed by the Physikalisch-Technische Bundesanstalt (FederalGerman Bureau of Standards) inBrunswick. This federal test agencyuses Audio Analyzer UPD and thespecial application program to carryout type-approval tests on hearing aids.Every hearing aid manufacturer thatuses Audio Analyzer UPD or UPL canbe sure that he will meet all relevanttechnical requirements for type-approv-al tests.

Tilman Betz

REFERENCES

[1] Kernchen, W.: Audio Analyzer UPD generatesand measures analog and digital audiosignals. News from Rohde & Schwarz (1992)No. 139, pp 13 – 15

[2] Kernchen, W.: Audio Analyzer UPL – audioanalysis today and tomorrow. News fromRohde & Schwarz (1996) No. 151, pp 4 – 7


Application notes

ear as far as possible. Only theacoustic signal should be amplified, theinherent noise of the hearing aid beingkept as low as possible. The NOISEmeasurement is made to determine theacoustic noise pressure output level ofthe hearing aid with no input. Fromthese data and the gain of the hearingaid, the equivalent input noise pressurelevel can be calculated. Naturally,external noise must be sufficiently

FIG 3 Output sound level vs input sound level ofhearing aid at 500, 1000, 1600, 2500 and4000 Hz


Europe is not the only place where digital GSM and DECT networks haveflourished. Variations of these networksare taking hold all over the world, butthe market is by no means saturated.Manufacturers of mobile phones stillhave to woo the customer to win orders.All manufacturers are able to supply the basic functions required for mobileoperation and so customers now tendto go for features that can be assesseddirectly rather than the provision of basic features. Design and quality arefeatures that can clinch a purchase.

Using the right measurement technolo-gy has a positive effect on quality. Fromthe outset, Rohde & Schwarz has de-signed its GSM and DECT productiontesters to guarantee quality at the RFinterface [1; 2]. In the meantime, thishas come to be thought of as a stan-dard basic function. The situation is different as far as the AF interface of themobile is concerned. Within the accept-able quality range, quality differencesin the audio signal can be clearly dis-cerned by the user and this may influ-ence his decision to buy.

For this reason, Rohde & Schwarz hasconsiderably upgraded the AF meas-urement capabilities of its GSM/DCS1800/DCS 1900 and DECT radio-communication testers. Multitone audioanalysis has been added to functionssuch as AF generator, AF meter withrms and peak value meter, distortionmeter and frequency counter. In the

new measurement mode, CMD (FIG 1)generates up to 14 user-selectable fre-quencies in the range 50 Hz to 8 kHzwith individually adjustable levels (canalso be switched off). After the multi-frequency signal has passed throughthe DUT, CMD performs narrowbandvoltage measurements at these frequen-cies.

Measurements

Fast frequency response measurement(FIG 2): the user selects 14 points on thefrequency response curve and setseach frequency to the same level.Measuring the output levels of the DUTat these points gives the frequency response of the DUT. If there are fre-quencies which have passed throughthe DUT and are far below the possiblemeasurement limits, the measurementrange for these particular frequenciescan be extended by increasing the level on the generator side. Since allfrequencies are measured simultane-ously, the frequency response measure-ment is fast in spite of the narrow measurement bandwidth (approx. 2 sat 1 Hz). This measurement is a goodchoice for noisy production environ-ments as most of the external noise isexcluded thanks to the narrow measure-ment bandwidth.

True harmonic distortion measurement:the distortion measurement performedup to now was in fact a SINAD meas-urement, ie the total signal is referencedto a signal from which the fundamen-tal has been removed. With multitoneaudio analysis individual harmonicscan be singled out. The fundamentalfrequency at a certain level is set on thesignal generator. Then up to 13 har-monics are chosen with the signal gen-erator switched off. On the output side,narrowband measurements on all thefrequencies provide information aboutthe whole harmonic spectrum.

Application notes

Quality testing of mobile phones using multitone audio analysis of Digital Radiocommunication Tester CMD

FIG 1 To handle more stringent quality require-ments for GSM and DECT mobile stations, DigitalRadiocommunication Tester CMD from Rohde &Schwarz was upgraded with powerful AF meas-urement functions. Photo 40 944/1


Intermodulation measurement (FIG 3):like distortion measurement, this meas-urement too is used to check the linear-ity of the DUT. Two test tones instead ofone are used in this case, however. Theintermodulation products occur at pre-cisely predictable frequencies whichare a function of the two test tones. Con-sequently, a level is assigned to two ofthe frequencies and the others are set tothe expected intermodulation frequen-cies with no generator signal present.

Aliasing products: prior to transmittinganalog voice signals in a range from300 Hz to 3.3 kHz on the digital network, the signals are sampled at arate of 8 kHz. Frequency componentsabove 4 kHz must not reach the sam-pler as otherwise unwanted aliasingproducts would be produced. Knowingthe test frequency and the sampling fre-quency, the aliasing frequency can bedetermined precisely. The level is thenmeasured at these points.

Control and operation

Signal paths (FIG 4): CMD’s AF inter-face with its new multitone analysis facilities and the “old” AF test functionswith generator and analyzer can beconnected to the front-panel connectorsor to CMD’s ADPCM interface for DECTapplications. If CMD is equipped witha Speech Encoder/Decoder CMD-B5for GSM, the AF interface may be internally switched to this option.

Operating modes: in the single-shotmode, the generator can be started before the analyzer to allow the DUT to settle completely before the measure-ment is started. Normally the continu-ous measurement mode is chosen formanual operation, results being up-dated every second. If the operator sus-pects that there is an out-of-tolerancecondition, continuous measurementcan be stopped to examine the outliermore closely.

Analysis using tolerances: as with any other CMD result, tolerances maybe set for the results obtained from multitone audio analysis on a go/nogobasis. With the aid of this function,

a single go/nogo outcome can be obtained from every group of 14 results– in other words, a single, accurateconclusive result can be obtained froma complex measurement.

Result display: the great variety of display and scaling modes – tailored to specific measurement tasks – makesreading of results easy and simplifiestheir interpretation. Any signal gener-ator level may be used as a referencefor the measurements or an indepen-dent reference value can be defined.As appropriate, log or linear scalesmay be chosen on CMD.

Thomas Maucksch

REFERENCES

[1] Maucksch, T.: Digital RadiocommunicationTester CMD60 – A favourably priced com-pact test set for series production of DECTmobiles. News from Rohde & Schwarz(1995) No. 149, pp 13–15

[2] Vohrer, M.: Multimode RadiocommunicationTester CMD for GSM, PCN, PCS and DECTmobiles. News from Rohde & Schwarz(1996) No. 150, pp 53– 54


Application notes

FIG 2 AF frequency response. Results from multitone audio analysis are always displayed as bargraphs. Bars represent points selected on DUT’s AFfrequency response.

FIG 3 AF intermodulation measurement. Two larger bars represent testtones, smaller ones at right and left unwanted intermodulation products meas-ured by CMD at high speed over wide dynamic range.

FIG 4 Setup for measuring frequency response,distortion, intermodulation and aliasing in micro-phone path of DUT (here DECT portable part).Similar setup is used for measurements in loud-speaker path.

ROHDE & SCHWARZ

ADPCM

AF voltmeterRF Mod. gen.

DUT

CMD


Automatic testing often requires onlyrelatively simple functions for settingand evaluating a DUT, eg a mobilephone. For these purposes IndustrialController PSM (FIG 1) [1; 2] isequipped to standard with the factoryuser port (FUP), a universal interface.This means that a multitude of applica-tions can be implemented without anyadditional hardware. The supplied soft-ware library considerably reduces thetime required to become familiar withthe FUP and its operation.

Function blocks

The factory user port provides the fol-lowing functions for use with externalequipment (FIG 2):• 10-bit A/D converter, four channels,

0 to 5 V,• eight digital inputs and outputs,• pulse width modulator which can

also be used as an analog output,• optocoupler input,• optocoupler output,• two relays, each with a changeover

switch,• supply voltages for external circuits.

A microcontroller controls all these func-tions. It is connected to the ISA bus inPSM, from where it can be convenientlyoperated via the FUP software interfaceusing the following languages:• R&S BASIC,• Microsoft VisualBASIC for DOS,• Microsoft VisualBASIC for Windows,• Microsoft BASIC PDS 7.0,• Microsoft QuickBASIC,• Microsoft C for DOS,• Microsoft C for Windows,• Borland Pascal 7.0,• Microsoft Pascal 4.0.

Applications

Since Industrial Controller PSM waslaunched on the market approx-imately two years ago, Rohde &Schwarz has published more than ten application notes, which can beobtained by all users from their R&Srepresentative. Relevant applicationsfor the FUP are DC measurements (V, I, R), AC line monitoring, batterytesting and remote control of satelliteantennas. The first three applicationsdemonstrate the powerful languageinterface of the FUP, whereas thefourth makes use of its complete rangeof functions and involves writing firm-ware.

Application notes

Tailor-made applications in industrial automationwith factory user port for Controller PSM

DA

10-bit A/D converter 0 to 5 V

Programmable pulse signal

8-bit digital I/O

0% 100%

Power supply

Relays

Optocoupler

12.00 5.00

+12 V -12 V GND +5 V

FUP connector at rear of unit

FIG 2 Functions of factory user port for IndustrialController PSM

FIG 1 Industrial Controller PSM is ideal for auto-matic test facilities. Photo 41 488/1


DC current and voltage measurementsIn many cases this simple application(Application Notes 1CMAN19 andAN20) makes an external IEC/IEEE-bus multimeter superfluous; it demon-strates DC voltage or DC current meas-urements. Sampling every 100 ms (inthe VisualBASIC example) means thatslowly varying quantities can also bemeasured. There are four measurementranges: 10 V, 100 V, 1 A and 10 A.Each measurement range is assigned toone of the four A/D converter inputs viaa matching circuit. The minus pole ofthe signal to be measured is connectedto PSM’s ground. Application Note AN19describes control under VisualBASIC,whereas AN20 deals with control underRohde & Schwarz BASIC. R&S BASIChas a steep learning curve, as the interpreter immediately executes anycommand that is entered.

AC line monitoringThis application example (ApplicationNote 1CMAN22) describes how tomonitor the AC line. The optional DCSupply (PSM-B3) must be fitted to PSMif you want to measure power supplydrops or failures. This option can alsobe modified to give an uninterruptiblepower supply. AC line monitoring is performed under VisualBASIC. The rectified AC voltage which has beentapped via a transformer is measuredperiodically. Supply failures and theirdurations are recorded. The AC voltage is also monitored so that smallfluctuations can also be detected.

Battery testsThis example (Application Note 1CMAN25), which is somewhat morecomplex than the applications men-tioned above, demonstrates the moni-toring of various characteristics relatedto rechargeable batteries. The follow-ing tests can be performed with this application:• determination of battery capaci-

tance,• absolute and differential tempera-

ture measurement,• monitoring of charging,• discharge monitoring.

a maximum voltage or a maximum temperature is exceeded. The battery isnow fully charged and its capacitancecan be checked in another dischargecycle. The VisualBASIC program sup-plied shows two graphic windows withcurves describing the battery voltageand temperature as they change duringthe charge or discharge cycle, the battery capacitance is indicated as a function of the charge or dischargecycle (FIG 3).

Remote control of satellite antennasThis example (Application Note 1CMAN10) demonstrates the FUP’s full range of functions in combinationwith PSM. The built-in microcontroller,which has software that can be loadedfor particular applications, uses datapreprocessing to solve very complexmeasurement tasks. If a satellite anten-na is controlled by a built-in controller,the data signal is a sequence of pulses,

loaded into the FUP microcontroller andstarted. A software library has beensupplied to make it easy to send data tothe microcontroller and so position theantenna.

Joachim Stegmaier

REFERENCES

[1] Bues, D.; Stegmaier, J.; Vahldiek, D.: Indus-trial Controller PSM – Automated testing and control in production and lab. Newsfrom Rohde & Schwarz (1994) No. 146, pp 19–21

[2] Bues, D.: Industrial Controller PSM for pro-duction rationalization. News from Rohde &Schwarz (1995) No. 147, pp 32–33


Application notes

This application also provides an intro-duction to programming the FUP usingVisualBASIC and shows you how to write a Windows program too. The battery under test is first discharged until a preset minimum voltage isreached. It is then recharged until either

different pulse widths representing a 1or a 0. As these pulses have to be veryshort (64 or 86 µs), an independent microcontroller such as the one provid-ed in the FUP is an ideal pulse source.In this case, software which has beenspecially designed for this task is

FIG 3Screen display

for battery testingapplication


When it was first introduced, short-wave data transmission was limited to200 bit/s. This was because of theproblem of multipath propagation inshortwave communications. Errorcontrol methods such as FEC (forwarderror correction) and ARQ (automaticrepeat request) ensure minimal bit errorrates. Methods of compensating formultipath effects could however not bedeveloped cost-effectively until power-

ful signal processors came along. Theymade it possible to increase the datarate to over 2400 bit/s, which becamethe standard for most shortwavemodems for a period of several years.

In HF Modem GM2100 (FIG 1), Rohde& Schwarz has now pushed the speedlimits for data transmission even further.This modem from the XK2000 family of shortwave radio equipment [1]makes data transmission rates up to5400 bit/s possible. Adaptive methodsare used for matching the data trans-mission rate to the quality of the path:under favourable propagation con-ditions, transmission is at maximumspeed, under less favourable condi-tions, the number of error control bits isincreased. This results in a considerableincrease in the effective data through-put for a typical shortwave link.

Data modem GM2100 has threesignal formats for data transmission:• a Rohde & Schwarz signal format,• a signal format to MIL-STD-188-110A

(single-tone method),• a signal format to STANAG 4285.

The R&S signal format is compatiblewith those of data modems GM857C4[2] and GM2000. For GM2100 it wasoptimized to give data rates between900 and 5400 bit/s. FIG 2 shows thestructure of a frame with this signalformat transmitted by GM2100. IfGM2100 is used in conjunction with an ALIS processor [3], the transmissionrate is automatically matched to theradio-link quality and to the require-ments of the transmission protocol, andoptimum utilization of the transmissionchannel is also ensured. During linksetup, the ALIS processor automaticallycalculates the maximum possible link

Application notes

Fast adaptive data transmission on shortwave at up to 5400 bit/s with HF Modem GM2100

FIG 1 HF Modem GM2100 for shortwave datatransmission at up to 5400 bit/s

Photo 42 569

FIG 2 Frame structure of Rohde & Schwarz signal format for HF Modem GM2100

Preamble: 192 symbols Data + FEC: 48 symbols Postamble: 64 symbolsTest sequence: 16 symbols

Further data blocks1 data block

80 ms 26 2/3 ms 26 2/3 ms


data rate. This gives full compatibilitywith the Rohde & Schwarz seriesHF850 and XK2000 HF systems.

The HF modem phase-modulates the HFcarrier, using 2PSK, 4PSK and 8PSK. 2PSK is used for a data rate of 900 bit/sand 4PSK for 1800 bit/s. As fewerphase states are used for transmission,2PSK and 4PSK increase the reliabilityof data transmission for links of lowerquality. 8PSK is used for high-quality HF paths. To further increase the datarate in the latter case, the redundancyof the FEC of a transmitted block can be adjusted. In this way, transmissionrates up to 5400 bit/s can be achieved(TABLE 1).

A great advantage of the transmissionmethod employed by GM2100 isautomatic detection of the receivedsignal data rate by means of a codereceived at the start of reception. Thismeans that the receiving data modemneed not be told the data rate of thetransmitting modem. The ALIS proces-sor makes use of this feature and trans-mits RSX.25 protocol data at a lower

rate. Even though the quantity of thesedata in relation to the user data isvanishingly small, the protocol data areextremely important for the trans-mission protocol. This intelligent controlfunction therefore greatly enhancesdata transmission reliability.

The high transmission speeds achiev-able, in conjunction with the RSX.25protocol, give a synchronous data rateof 3600 bit/s at the data terminal in-terface for high-quality radio links. Thiscorresponds to an asynchronous datarate of 4480 bit/s for an interface set-ting with eight data bits, one stop bitand no check bit, ie to a practically con-tinuous data stream of 4500 baud. TABLE 2 shows the data transmission times for an HF system with System Pro-cessor MERLIN [4], HF TransceiverXK2100, the ALIS processor and HFModem GM2100.

For transmissions using standardizedsignal formats to MIL-STD-188-110A,8PSK at a rate of 2400 symbols persecond is employed. Asynchronousdata rates between 75 and 4800 baud

and synchronous data rates between75 and 4800 bit/s are possible. FECfor error control can be set according tothe selected transmission speed. Inter-leaving of the transmitted data with aninterleaver length between 0.6 and4.8 s can also be selected.

For transmissions using STANAG 4285signal format, similar data rates as withMIL-STD-188-110A can be achieved bymeans of various modulation methods.Here too, a long or short interleaving time can be selected.

Although MIL-STD and STANAG signalformats do not allow as high a datathroughput as the R&S signal format,their availability on GM2100 ensuresinteroperability with stations usingthese standards. GM2100 gives maxi-mum transmission rates at low BERs,making shortwave data transmissiontechnically comparable with worldwidesatellite transmission or PTT lines.

Günter Wicker; Gerhard Greubel

REFERENCES

[1] Helmke, B.; Wachter, G.: HF TransceiverXK2100 – Digital shortwave for future-proof,long-haul communication. News from Rohde& Schwarz (1994) No. 144, pp 4 – 7

[2] Hackl, H.: Secure data transmission with2700 bit/s on shortwave links. News fromRohde & Schwarz (1994) No. 146,pp 29 – 31

[3] Greiner, G.: Reliable shortwave with ALIS.News from Rohde & Schwarz (1987)No. 116, pp 47 – 50

[4] Kneidel, T.: System Processor MERLINGR2000 – Powerful processor stands toughestconditions. In this issue, pp 12 – 13


Application notes

Modulation Info bits Redundancy bits Code rate FEC Net data ratemethod [%] [bit/s]8PSK 144 0 No FEC 0 54008PSK 120 24 5/6 17 45008PSK 96 48 2/3 33 36008PSK 72 72 1/2 50 27004PSK 36 36 1/2 50 18002PSK 18 18 1/2 50 900

TABLE 1: Possible data rates for Rohde & Schwarz signal format for HF Modem GM2100

Typical data volume Typical data volume Data Transmissionnon-compressed compressed reduction time with GM2100

Text 2.5 Kbyte/page 0.9 Kbyte/page 64 % 2.5 s

Fax 30 Kbyte/page 24 Kbyte/page 20 % 63 s

Video 490 Kbyte/page 15 Kbyte/page 97 % 44 s

TABLE 2: Data transmission times for typical shortwave applications


2.4 Frequency-shift keying

All the types of modulation describedso far have been linear. The (doublesideband) baseband spectrum is shifted linearly in the RF range. Themodulators used are memoryless asneither the instantaneous phase ϕ(m)nor the instantaneous amplitude a(m)are functions of previous values ϕ(m-p)or a(m-p).

Another way of transmitting digital signals is mapping the M-ary base-band signals onto RF signals with M different frequencies. This type of mod-ulation is referred to as M-ary frequen-cy-shift keying (FSK). FSK is not linearand the RF spectrum is a Bessel spec-trum which has frequency componentsthat are not present in the original sig-nal.

A simple form of frequency-shift key-ing with no memory can be imple-mented by switching between M oscil-lators each with a different frequency.When this is done, the phase of the RFsignal is random. The disadvantageof this type of FSK is that the RF spec-trum has large sidelobes. Frequency-shift keying with continuous phaseshifts (continuous phase frequency-shift keying, CPFSK) does not havethis drawback. A CPFSK modulatorcan be implemented with a voltage-controlled oscillator (VCO) or an I/Qmodulator.

Binary FSK is the simplest form of FSK and is described in terms of thetwo signals

s1(t) = A · cos[2π(fc + ∆f)t]

and (12)

s2(t) = A · cos[2π(fc – ∆f)t]

2.5 Correlation and distancebetween signals

The parameters used to represent in-formation are not the only differencesbetween the various types of modula-tion. There are also differences in theirsensitivity to external interference and,as mentioned previously, efficient use ofthe available RF bandwidth. A numberof parameters that indicate how well amodulation method can transmit infor-mation on a particular radio channelhave to be considered. In chapter 1,modulation was defined as the assign-ment of one of the M possible signalsthat could be transmitted to a block of k bits. The signal is distorted duringtransmission. The purpose of demod-ulation in the receiver is to detect thesignal in the presence of the noisewhich has been introduced duringtransmission and to distinguish it fromthe other M -1 signals that could havebeen sent. It is obvious that a mod-ulation technique based on a set of M signals can best fulfil its task if theseM signals are as different from eachother as possible. Mathematically, the degree of similarity between twosignals is expressed in terms of theircorrelation factor

*s1(t) · s2(t)dtTρ = —————————— (13)

*s21(t)dt

T

or in terms of their Euclidean distance

D2 = *T[s1(t) – s2(t)]2 dt

= E1 + E2 – 2√———E1· E2

l · ρ (14)

where E is the mean energy over the duration of the symbol.

When E1 = E2, as is the case with PSKand FSK, this equation simplifies toD2 = 2 · Ebit · (1– ρ). (15)

For binary ASK (s2 = 0) this formulagives a distance DASK = √—

El and

DBPSK = 2√—El for BPSK (s2 = –s1).

There are two distance values forQPSK, Dmax = 2√—El and Dmin = √—2l√—El.

The Euclidean distance for FSK dependson the modulation index; in the case of CPFSK with a modulation index of0.5 DCPFSK = √—2l √—El. This is the basis for the modulation technique used forGSM radio networks.

2.6 Coherent demodulation

When RF signals are phase-modulated,the resulting spectrum does not have acomponent at the carrier frequency.This means that the relationshipbetween the current phase which car-ries the information and the phase ofthe unmodulated carrier is not directlyavailable. Therefore, a complex methodis used to regenerate the carrier so thatit has its original frequency and phase.There are several frequency synchron-ization techniques that can be used, forexample squaring the modulated signalonce or twice and then dividing thedoubled frequency by two (BPSK) or thequadrupled frequency by four (QPSK).Another approach is to periodicallytransmit an unmodulated frequencywhich the local oscillators in the re-ceiver can lock onto. Usually the exactphase is obtained by means of specialsequences (training sequences) con-tained in the datagrams. The cross-correlation of the received sequenceswith identical sequences stored in thereceiver provides phase corrections forthe local oscillators.

A signal of the form cos(2πft) and anorthogonal signal of the form–sin(2πft) = cos(2πft + π/2) are recovered from the regeneratedcarrier.

Both components are multiplied by thereceived signal A(t) · cos(2πft + ϕ(t))and the following are obtained:

Refresher topic

Digital modulation and mobile radio (III)

2 Basic modulationtechniques


A(t) · cos(2πft + ϕ(t)) · cos(2πft)

= 12–– A(t)[cos(ϕ(t)) + cos(4πft + ϕ(t))],

A(t) · cos(2πft + ϕ(t)) · cos[2πft + π2––]

= 12–– A(t)3cos[ϕ(t) + π

2––]

+ cos[4πft + ϕ(t) + π2––]4. (16)

The following terms remain when RFcomponents are filtered out (FIG 7):

12–– A(t)[cos(ϕ(t))]

and (17)

12–– A(t)3cos[ϕ(t) + π

2––]4= 1

2–– A(t)[–sin(ϕ(t))]

However, as equation (3) shows, theseare the modulating signals of the I andQ carrier components to within a con-stant factor and, as equation (6) shows,they are the components of the complexenvelope of the modulated signal towithin the same constant and the signof the imaginary part. If the originaldata are to be recovered, the inverse of the mapping onto the signals cI(t)and cQ(t) or onto the complex envelopeu(t) must be found.

Coherent demodulation must be usedfor systems using true phase modula-tion, provided that differential coding isnot used for the data. When phaseshifts and not absolute phases are usedto encode information, this is referredto as differential coding. Coherent de-modulation can, however, be used forall other types of modulation. In gener-al, it performs better than non-coherentmethods, ie lower bit error rate for thesame ratio of bit energy to noise powerdensity.

3 Modulation methods formobile-radio networks

The last chapter would lead one to conclude that BPSK has the greatest immunity to noise introduced by the

transmission channel. Indeed, aftertransmission through a channel that only adds white noise to the wantedsignal, referred to as an AWGN channel (added white Gaussian noise),BPSK is optimal with respect to the bit error rate as a function of the bit energy to noise power density ratio Ebit/N0. This type of modulation is,therefore, used as a benchmark for other types of modulation. The band-width efficiency is inadequate how-ever. Although M-ary PSK and QAMhave considerably better bandwidth efficiencies, they exhibit small Euclid-ean distances, which means that theirsusceptibility to noise on the transmis-sion path increases as the number ofsignal states increases. The implemen-tation of modulators and demodulatorsalso becomes more and more involvedas the complexity of the modulationtechnique increases.

Ostensibly, when compared with BPSK,QPSK seems to be a good trade-offbetween efficient use of bandwidth, immunity to noise and technical com-plexity because of its mean minimal difference in Euclidean distance and its bandwidth efficiency, which is twiceas good. By contrast, CPFSK as imple-mented in GSM networks requires farmore complex hardware and so on the face of it does not appear to be theoptimum choice.

However, a more careful analysis of theband-limited RF signals and their suit-ability for radio transmission gives an entirely different perspective. Band-limited M-ary PSK exhibits spurious inci-dent AM modulation of the RF carrier.The reason for this is that the magnitudeof the RF signal vector changes duringphase transitions which are slower thanthose that occur with modulation with-out band-limiting. This effect is particu-larly marked when the phase changesby 180° (transition from 00 to 11 forBPSK and 10 to 01 for QPSK), the carrier being reduced to zero for atime. The carrier is reduced to 0.7 of its maximum value when the phasechanges by 90° and to 0.38 of its max-imum value when the phase changesby 135° (possible phase shift for 8-PSK)– this is equivalent to attenuation of 8.4 dB. This precludes the use of effec-tive but nonlinear C-class amplifiers inmobile radios and means that linear A-class amplifiers are required for the output stage. It also makes it moredifficult to recover the carrier from themodulated signal, which is essential forcoherent demodulation.

To be continued Peter Hatzold

Refresher topic

FIG 7Coherentdemodulation

cl(t)

cQ(t)

-sin (2 π f t)

cos (2 π f t)

A(t) • cos (2πft+ϕ(t))


Propagation Wizard, or PropWiz, is anew program which allows the qualityof a shortwave link between any twopoints in the world to be predicted in anextremely easy way. PropagationWizard calculates the reliability of alink, ie the available time for a desiredS/N ratio and the appropriatefrequency range. Results are displayedas well laid-out graphics on a monitor(FIG). Colour printouts can be pro-duced on any colour printer. The avail-able time for a link is indicated in hoursper day.

A free demo version of this program isnow available for the first time from theRohde & Schwarz Web site and can bedownloaded by anyone wanting to tryit out (address: http://www.rsd.de).

With its simple, self-explanatory userinterface (Windows 3.x or 95) and thehigh forecast quality, PropagationWizard is unique on the market. Ittakes into account the characteristics ofRohde & Schwarz transceivers of allpower classes (HF850/XK2000),modulation methods (eg Data ModemGM2000) and, most importantly, the characteristics of transmitting and receiving antennas (eg HX002,AK471). The vertical radiation pat-terns (ie gain as a function of elevationangle and frequency) are used in calculation. Customer-specific require-ments and parameters can easily beimplemented.

To determine S/N ratio, not only thereceived field strength but alsoatmospheric, galactic and man-madenoise at the site of reception are takeninto account in accordance with the relevant CCIR recommendations.Thanks to Propagation Wizard, thecomplex chain of link-quality calcu-lations can now be performed by justpressing a key or clicking a mouse.Propagation Wizard is, therefore, also

ideal for the exhaustive, high-reliabilityanalysis of large and complex radionetworks, including all interconnec-tions, at a relatively high speed.Previously, calculations of this kind hadto be performed using the followingsequence of steps:

1. Calculation of the field strength atthe reception site using a program.2. Determination of all noise and inter-ference at the reception site by meansof CCIR tables (depending on place,time of day and season).3. Calculation of S/N ratio taking intoaccount inherent receiver noise, band-width and the receiving antenna.4. Comparison of calculated S/N ratiowith minimum nominal ratio for modu-lation method used.5. 24-fold repetition of steps 1 to 4 forall hours of the day.6. If input parameters were changed,(eg to correct antenna gain for thecalculated frequency range), allprevious steps had to be repeated.7. All calculations and evaluationshad to be repeated for new transmis-sion or reception sites.8. Results had to be presented asgraphics for a full assessment.

Propagation Wizard spares the user allthis work and gives the result in no time.Calculations can be performed withslightly altered parameters any numberof times, allowing the effect of specificparameters to be determined (eg mini-mum required transmitting power).

Here are the special features of Propa-gation Wizard again at a glance:

• extremely easy operation throughself-explanatory Windows user inter-face,

• Windows help function (context-sensitive) always available in thebackground,

• based on proven algorithms,• includes all relevant shortwave link

parameters in the calculation,• takes into account the characteristics

of Rohde & Schwarz shortwavesystem components,

• takes into account the verticalpatterns of Rohde & Schwarz anten-nas,

• calculates the available time andoptimum frequency range for ashortwave link,

• displays results as graphics on themonitor,

Software

PropWiz – Windows program for shortwave radio link prediction

Result printout ofshortwave linkcalculation made withPropagation Wizard


• outputs colour hardcopies on aprinter,

• performs all calculations very rapidly.

Propagation Wizard is available intwo versions:• standard version for normal PC

(min. 800 x 600 pixels),

• laptop/notebook version (640 x480 pixels).

Both versions are available as freedemos with Munich as the receptionstation. All features of the programincluding the printing function are avail-able, allowing prospective users to

Software

PatentFrequency-selective measurement and displayof frequency-dependent test parameters

In the field of RF measurements, there are an in-creasing number of analyzers for frequency-selective analysis of frequency-dependent test pa-rameters over a frequency range of interest. Forexample, there are spectrum analyzers that displaythe amplitude of a test signal as a function offrequency over a wide frequency range in nearlyrealtime on a CRT (eg Spectrum Analyzer FSA fromRohde & Schwarz). There are also networkanalyzers which have a tracking generator as wellas the frequency-selective analyzer (eg Scalar Spec-trum and Network Analyzer FSAS). Network ana-lyzers of this kind can be used for measuring the

amplitude versus frequency characteristics of a four-terminal network. There are also vector networkanalyzers that can measure both magnitude andphase. From the magnitude and phase, theimpedance of a device under test (DUT) can becalculated, for example, and from the phase/frequency curve the group delay. Network analyzersof this kind can, therefore, be used for measuring awide variety of DUT parameters. The main problemwith all the analyzers that have been referred to is,however, that they cannot be adjusted to obtainoptimum accuracy and measurement speed for aspecific measurement task or DUT.

The purpose of the invention is to provide an ana-lyzer similar to the one initially described that can beoptimally tailored to the measurement task to beperformed. This problem is solved for an analyzer asdescribed in the preamble of the main claim throughthe characteristic features of the analyzer. Usefulfurther developments, in particular for the design ofa network analyzer, result from the subclaims. Theinvention provides for optimum adjustment offrequency scaling (number and distribution of thefrequency steps) and the scaling of the test pa-rameters (eg amplitude, phase, impedance andgroup-delay scaling) to a specific task in varioussubranges of the overall frequency range. Forexample, when measuring the transfer character-istics of a lowpass or highpass filter, the overallfrequency range of the network analyzer is dividedinto two subranges (passband and stopband), andmeasurements are performed in the two subrangesusing different frequency scales and different testparameter scales (FIG). To perform measurementson a bandpass or a bandstop filter, it is expedient todivide the total frequency range into three adjacentsubranges, with the scaling of each range adaptedto the filter passband and stopband ranges, themiddle range having higher frequency and levelresolution than the neighbouring stopband ranges.Since the patented analyzer allows the user to selectthe number of frequency steps per subrange, theanalyzer’s measurement speed can be optimized,

which is very useful for aligning DUTs. The display offrequency or test parameter markers, eg levelmarkers, or of test parameter tolerance lines, egnominal level lines, during the measurement makesthe patented analyzer a highly versatile instrumentsuitable for a wide variety of measurement tasks, egfor measuring the selectivity characteristics of high-pass, lowpass, bandpass or bandstop filters. Thepatented analyzer can also be used for displayingvarious selectivity characteristics of a multiport DUT,for example a diplexer consisting of a lowpass anda highpass filter, in which case a multichannelinstrument would have to be used.

Extract from patent specification EP 473 949 B1Applied for by Rohde & Schwarz on 11 March1992Issue of patent published on 21 June 1995Inventor: Klaus Danzeisen

Used in Vector Network Analyzers ZVR

Reader service card 152/18 for furtherinformation on ZVR

DUTHigh-

frequency generator

Frequency- selective

meas. unit

Micro- processor

Lower stopband Passband

Upper stopband

1 10 100 990 1000 1010 2000 MHz 4000

Frequency marker

Scale unit 10 dB

Scale unit 1 dB

Scale unit 20 dB

Frequency marker

Level tolerance line

Level marker

Level marker

Level marker Frequency

marker

Display

make a complete assessment of Propa-gation Wizard.

Dr. Hans Waibel; Peter Maurer



CMD55 (FIG 1) is a compact unit fortesting GSM, PCN and PCS mobilephones in advanced service andproduction environments [1; 2]. Thetester has been upgraded with a varietyof new measurement functions tocomply with the latest requirements forthese application areas.

The following new characteristics makeCMD55 ideal for use in mobile-phoneproduction:

To measure the RF parameters ofmobiles, the tester has to simulate abase station so that a call can be set up.The complete signalling procedure fora location update requires up to 10 s,but this may be too long for a pro-duction environment. CMD has twoways of saving valuable processingtime. As well as the complete signallingprocedure, there is also an abbreviatedsignalling mode where all signallingmessages not required for testing areeliminated. Testing can be speeded upeven further if the IMSI (international

mobile subscriber identity) is known, as a direct call can be made from themobile to CMD (direct paging). Produc-tion departments generally use a testSIM card with a known IMSI.

Production tests on mobile phones haveto be performed at different TX powers.The signalling procedure required for apower change is also very elaborate.Here too, test duration can be cut bychanging channel in CMD to changeTX power, ie by choosing the samechannel but with different power. Thesignalling procedure is much shorter inthis case.

To speed up the remote-control mode,the outgoing and incoming remote-control commands are displayed on the CMD screen, but not the menus re-quired for manual control. This com-mand display function is extremely use-ful for writing and testing remote-controlprograms in the test phase. In normaloperation the command display func-tion can be disabled, giving a furtherincrease in speed. When used in auto-matic repair test setups, CMD can bedirectly switched over from remote tomanual. The menu level and the signal-ling status are retained however. Thismeans that immediately after fault de-tection by the automatic test program,the fault can be analyzed in more detailusing the graphics menus in the manu-al mode.

The processing speed of the hardwarecomponents in CMD55 has also beenincreased thanks to a faster micro-processor system. The modular designof CMD means that the new controllermodule can also be retrofitted to testsystems that have already been supplied.

The following new features enableCMD55 to be used in development andquality assurance of mobile phones.

Panorama

Digital Radiocommunication Tester CMD55with new measurement functions

FIG 1 Digital Radiocommunication TesterCMD55 Photo 40 946

FIG 2 Timing advance test menu FIG 3 Network definition menu


A GSM phone has to have the correctfrequency and time slot synchro-nization with respect to the test setupwhich is acting as the base station.CMD can measure how early or latethe mobile is transmitting, ie it performsa timing error measurement. A timingadvance test can also be performed. Inthis case CMD tells the mobile by howmuch it should send too early or late so that it can make a correction andthen measure the time offset (FIG 2).This function is required for delay cor-rection when base stations are a largedistance away.

To check the dynamic RF characteristicsof mobile phones, one of CMD’s fourdifferent frequency hopping sequencescan be activated by a simple keystroke.A realtime speech coder/decoder(option CMD-B5) is available for meas-uring AF parameters. It is operated in

conjunction with the AF measurementunit comprising a voltmeter, distortionmeter, bandpass filter and AF genera-tor (option CMD-B41). After making aconnection to the AF interface of themobile’s hands-free facility or attachingan acoustic coupler, the AF character-istics of the mobile can be measuredprecisely.

The user of CMD55 may specify a num-ber of signalling parameters (FIG 3) tosimulate different networks for exam-ple. This means that the roaming be-haviour of mobiles can be tested in thehome network, or in others, by usingspecial network SIM cards. If there area large number of neighbouring cells,the mobile’s hardware and softwarehave to handle the increased load. Toassess the effects of the extra workload,the type of neighbouring cell and their number can be selected on CMD.

Prior to measurements, discontinuousreception or discontinuous transmissioncan be set on the mobile phone. Ca-pabilities like setting the mobile out-put power or choosing “registrationbarred / not barred” mean that CMDcan handle very specialized applica-tions.

Werner Mittermaier

REFERENCES

[1] Mittermaier, W.: Module test with DigitalRadiocommunication Tester CMD52/55.News from Rohde & Schwarz (1995)No. 149, pp 36 – 37

[2] Vohrer, M.: Multimode RadiocommunicationTester CMD for GSM, PCN, PCS and DECTmobiles. News from Rohde & Schwarz (1996)No. 150, pp 53 – 54


Panorama

ACCESSNET® – a solution for communicationsin Russia

only limited availability to the user. In industrial centers, mobile telephone networks to NMT and GSM standardsare being implemented, but this meansenormous investment and operatingcosts for the network operators and subscribers.

The ACCESSNET ® trunked-radiosystem from Rohde & Schwarz, basedon the European MPT 1327 signallingstandard, is the ideal solution for the re-quirement profile of potential networkoperators and users in Russia. Thanksto modular design, communicationsystems from compact local systems toregional and supraregional trunkedradio networks can be implemented at comparatively low investment cost

Following market liberalization there islarge demand for telecommunicationsin Russia which cannot be met by theexisting telephone network. Telecom-munication facilities in Russia have notreached the same level as those inhighly developed industrialized na-tions. There are many places where thecopper-based PSTNs are obsolete,overloaded and unable to cope withthe growing demand.

In the wake of the free-enterprise economy, private network operatorsare investing in mobile communicationnetworks. Most of these systems arepatched together from conventional radio components, offering a limitedrange of functions and in most cases

FIG 1 Russian type-approval certificate forRohde & Schwarz base station ND950 for pri-vate trunked-radio networks


[1 to 3]. The multitude of supplemen-tary call types and data transmission fa-cilities of these systems offers a muchwider range of services to the subscri-ber than any cellular phone system.

Supraregional frequency assignmentfor trunked-radio systems by the appro-priate authorities is much easier than it

is for a great number of conventionalsystems. If licences are granted toselected network operators who maketheir network infrastructure available tovarious user groups, more efficient usecan be made of the available fre-quency resources.

Rohde & Schwarz anticipated thedemand for communications in Russiaearly on, and since 1994 has beenseeking closer cooperation withRussian partners to consolidate a basisfor future business relationships. Sincetype approval of the ACCESSNET®

trunked-radio system is a preconditionfor supplying and commissioning, it

was given top priority. Rohde &Schwarz is now one of the firstmanufacturers to be granted a Russiancertificate for a trunked-radio system –ACCESSNET® (FIG 1).

The multi-faceted marketing activitieshave begun to bear fruit. Joint projectswere implemented with local system integrators in Moscow and Novosibirsk(FIG 2). Two systems are already in op-eration, four others are to be installedshortly. Operators of the trunked-radionetworks make useof the whole appli-cation spectrum of ACCESSNET® as apublic mobile radio system and for security services, harbour authoritiesand railway companies. The flexibilityof ACCESSNET® and its network ar-chitecture which is unique on the mar-ket, as well as Rohde & Schwarz’s ex-pertise with high-performance systems,are powerful arguments for Russia tochoose ACCESSNET® as a solution to its communication problems.

Andreas Schneider

REFERENCES

[1] Wagner, K.-H.: Trunked-radio systems suc-cessful all along the line. News from Rohde& Schwarz (1994) No. 146, p 55

[2] Schinke, U.; Klier, W.: RadiocommunicationSystem ACCESSNET®-D – Trunked radiogoes digital. News from Rohde & Schwarz(1995) No. 149, pp 28 – 31

[3] Wagner, K.-H.: A vision comes true – trunkedradio for United Arab Emirates. News fromRohde & Schwarz (1995) No. 151,pp 50 – 51


Panorama

FIG 2 Presentation of ACCESSNET® trunked-radio system at SIBCOM telecommunicationsshow in Novosibirsk Photo: author


The EMC laboratory of the safety stan-dards authority of Hesse (TÜH) offersthe whole range of measuring and testing facilities for electronic equip-ment of any kind. The test equipment isdesigned for measurements of electro-magnetic susceptibility (EMS) in the fre-quency range 10 kHz to 2 GHz andelectromagnetic interference (EMI) inthe range 5 Hz to 18 GHz. The meas-uring and test equipment supplied by Rohde & Schwarz (FIG 1) allows fast testing and flexible adaptation to different DUTs; the associated softwareensures optimum utilization of the ane-choic and shielded chambers installedby Siemens (FIG 2).

In the Kassel branch of the Hesse technical authority, new buildings for laboratories and offices as well as anopen-area test site occupy more than2000 m2; large rooms allow testing to directives on EMC, machinery and low-voltage equipment. Thanks to itscentral and easily accessible locationas well as its powerful technical outfit,the laboratory is an interesting partner

for manufacturers and importers of elec-tronic instruments and systems of up toapprox. 2500 kg.

The computer-controlled EMS testsystem from Rohde & Schwarz, forexample, allows measurements foracceptance tests to IEC 1000-4-3 andIEC 1000-4-6 in the frequency range

above 10 kHz. It includes a SignalGenerator SME, a relay matrix, threepower amplifiers, a MillivoltmeterURV5, a field-strength test system, atransmitting antenna as well ascoupling networks. The test system,which features higher power in thelower frequency range, is suitable forthe future development of standards. Ifrequired, measurements with differentantennas are possible from 1 MHz up-wards. The amplifiers can be manuallyor remotely controlled by means of thecomputer.

An EUT monitoring system transmitselectrical signals from the equipmentunder test to the operator’s position viafiber-optic cables. There the signalparameters can be read off the volt-meter or collected and logged by thecomputer. A video and audio systemalso operating via fiber cables is usedfor the visual and acoustic check of theEUT function. The computer-controlledEMI test system offers application-oriented facilities for measuring EUTs of up to 2500 kg on 3-m turntables inthe anechoic chamber and at the open-area test site. A sheltered buildingmade of special plastics is designed foropen-area testing at distances of 3 and10 m independent of the vagaries ofthe weather.

All measurement rooms have a 3 x 32 A power supply, a large number of power supply units for ancillary facilities as well as compressed-air, water, sewage and waste gas connec-tions. Regular servicing and calibrationof the measurement and test systemsguarantee high quality and reliability ofthe results.

Klaus Wunderlich (TÜH);Peter Busch

Reader service card 152/21 for further infor-mation on EMC test equipment

Panorama

Rohde & Schwarz test equipment in EMC test centerof safety standards authority of Hesse

FIG 1 EMC test system of safety standardsauthority of Hesse

FIG 2 Anechoic chamber in KasselPhotos: Eberth


The red carriage that can be seen onthe lines between Louvain and Aarschotor Gembloux and Namur in Belgiumlooks a bit bizarre. Its job is to measurethe field strength of transmissions in theradio network linking trains and basestations. Several years ago SNCB (Societé nationale des chemins de ferbelges) decided to set up a radio net-work linking trains and the railway con-trol center and ordered the test systemthey needed from Rohde & Schwarz (FIG). The system is not just for the na-tional rail network but will also be usedfor Eurostar, Thalis and the plannedParis – Brussels – Cologne – Amster-dam rail link.

“If the radio network is to workproperly, call setup must be reliableand there must be no lost call, in otherwords the received field strength mustbe adequate at all times”, explains theengineer responsible at the radiocom-munications department in the SNCB’sinfrastructure laboratories. The test car-riage has two functions. Firstly, it is usedto determine the number and positionsof the base stations. Secondly, it is usedto check the field strength once the net-

work has gone into operation. To dothis, the carriage has to travel the entireBelgium rail network in both directionstwice a year.

The test system is controlled by pulsesfrom a tachometer attached to one ofthe carriage’s axles. Spurious resultsdue to superposition are eliminated byperforming three measurements (asthree radio frequencies are used) everythree centimeters – at speeds of up to200 km/h. The results are analyzedstatistically to determine whether thereis a 95% probability of the 6 dBthreshold being exceeded on thenational network (95% of the time and95% of the coverage area); for high-speed lines 98% is the requirement.

Only 540 ms are available for measur-ing and processing the measurementresults, displaying them in realtime and generating graphs and tables. Ofcourse, this can only be achieved by areally fast system. Rohde & Schwarz uses three test receivers operating at afixed frequency around 460 MHz: oneESN and two ESVS10s. The equipmentused also includes three Process Con-

trollers PSM, one for data acquisition,one for statistical analysis of the dataand one for printing out, protocollingand presenting the data as graphics ona laser printer. The field strength valuesare also output on a YT plotter at thesame time, but without statistical analy-sis. The software used was specially designed for railway applications byLarisys, a French company.

Finally it should be mentioned that thecarriage is also equipped with an officefor field work, a workshop, a kitchenand a small room with a boiler and agenerator. “They could send us to themiddle of Siberia”, quipped the crew.“If we had an oil supply, we’d be totallyself-sufficient.”

Jacques Stellamans (SNCB Brussels)

Reader service card 152/22 for further infor-mation on railway communications test systems

Panorama

SNCB uses R&S test system for planning and qualityassurance in Belgian railway communications

Railway communi-cations test system of SNCB with twoTest Receivers ESVS10, one ESNand three PCsPhoto: SNCB


Audio Analyzer UPL has evolved out of UPD (but has fewer functions and slightly restrictedspecifications), is compatible with UPD and suit-able for mobile use; various options, eg digitalaudio interfaces.

Data sheet PD 757.2238.21 enter 152/23

GSM Go/NoGo Tester CTD52 and GSM/DCSGo/NoGo Tester CTD55 The data sheet hasbeen revised to include the new CTD55.


Digital Radiocommunication Testers CMD54,CMD57 The data sheet has been completely revised and expanded especially with regard toapplications and options.


Type Approval Systems for Mobile Radio Thisbrochure gives an overview of all systems avail-able.

Info PD 757.2321.21 enter 152/26

Software TS51K1 and TS55K1 ensures fast, effi-cient and economical measurements when usedwith GSM Coverage Measurement SystemsTS9951 or TS9955 from Rohde & Schwarz.


Shielded TEM Line S-LINE (150 kHz to 1 GHz)for EMS measurements with Rohde & Schwarzequipment is of compact design and available intwo sizes; 50 Ω, VSWR <3, max. 100 W.


EMI Software ES-K1 The range of drivers hasbeen expanded, the screen pictures have beenupdated.


EMI Test Receivers ESHS (9 kHz to 30 MHz) andESVS (20 to 1000 MHz) Receiver models 10 and30, which are still available, are now presentedin a single revised data sheet.

Data sheetESHS PD 756.3260.22 enter 152/30ESVS PD 756.9422.22 enter 152/31

Peak Power Sensor NRV-Z33 (30 MHz to 6 GHz;1 mW to 20 W; 50 Ω) Model 03 for TV trans-mitters and general-purpose measurements, model04 for TDMA radio technology.


Industrial Controller PSM Retrofit to Pentium (90 MHz) and 1-Gbyte harddisk as well as up-date of range of options.


Signal Generators SME and SMT (5 kHz to 6 GHz) Models 06 (6 GHz) are new in theproduct range.

Data sheetSME PD 757.0358.23 enter 152/34SMT PD 757.0364.22 enter 152/35

Receiver Part CT200RP (45 to 862 MHz; IF con-version), TV Receiver CT200RA (45 to 862 MHz;baseband conversion), Satellite Receiver CT200RS(950 to 2050 MHz; baseband conversion, option:ADR decoder) and QAM Modulator CT200QM(31 to 41 MHz; modulation of MPEG-coded video/audio signals onto IF) are extensions to the modular TV system CT200. The data sheetsfor Controller CT200CO, Upconverter CT200UPand Vision/Sound Modulator CT200VS havebeen revised.

Data sheet CT200-CO PD 757.0735.22 enter 152/36QM PD 757.1890.21 enter 152/37RA PD 757.1877.21 enter 152/38RP PD 757.1860.21 enter 152/39RS PD 757.1883.21 enter 152/40UP PD 757.0729.22 enter 152/41VS PD 757.0712.22 enter 152/42

Terrestrial Flight Telecommunication System JETCALL (1670 to 1675/1800 to 1805 MHz)The data sheet presents airborne equipment (toETS and ARINC) for public radiocommunications.


Radiolocation System NetTrap consisting of up tofour Direction Finders PA1555 (20 to 1000 MHz),Software WinLoc and a laptop enables full-duplexvoice and data transmission.


VHF/UHF Direction Finder DDF190 (20 MHz to 3 GHz) The revised data sheet furnishes detailed information about bearing accuracy aswell as general features.


Radio Paging Systems with Multi-Protocol Capa-bility This brochure from R&S BICK Mobilfunkdescribes the infrastructures of national and localsystems for public paging operators.

Info PD 757.2367.21 enter 152/46

TETRA – Trans European Trunked Radio for Professional Mobile Radio This brochure fromR&S BICK Mobilfunk informs about features, ba-sic and extra services of the new transeuropeanstandard.

Info PD 757.2373.21 enter 152/47

The world of test and measurement – our nameis synonymous with accuracy is the title of a bro-chure which presents the Test and MeasurementDivision of Rohde & Schwarz. The four strong pillars of test and measurement are mobile radio,EMC, general-purpose and RF measurements aswell as systems.

Info PD 757.2450.21 enter 152/48

New application notes

Network connection to a server via network cardwith CRTS/P/CAppl. 1CPAN04E enter 152/49

Measurement of transient responses in AGC circuits using Audio Analyzer UPD or UPLAppl. 1GPAN32E enter 152/50

Measurement of spurious emissions of GSM,DCS1800 and DCS1900 transmitters with spec-trum analyzers of the FSE familyAppl. 1EPAN17E enter 152/51

Measurement of power ramps of GSM, DCS1800and DCS1900 signals with spectrum analyzers of the FSE familyAppl. 1EPAN18E enter 152/52

Storing and loading complete test receiver datarecords via IEC/IEEE busAppl. 1EPAN20E enter 152/53

Exchanging data records between different testreceiver modelsAppl. 1EPAN19E enter 152/54

Schz

Information in print


Newsgrams

EMI test system at Siemens in MunichThe institute for quality engineering,trial and approval of Siemens in Munich operates a number of an-echoic chambers. The “giant an-echoic chamber”, brought up to thelatest technical standards in 1995 at a cost of some three million DM,has a useful inner space of 18 m x11.3 m x 7.4 m and can take eventhe biggest EUTs. Thanks to its hy-brid absorbers, ie plastic absorbers compounded with carbon on ferriteplates, it now allows tests in line withthe stiffer demands for field-strengthinstrumentation of ANSI-C 63.4,CISPR 16 and CISPR 22. EMI TestSystem TS9975 from Rohde &

Schwarz that is used here (photo left)consists of Test Receivers ESMI andESVS30 and a controller for the turntable and antenna mast. It worksfully automatically in the frequencyrange 20 Hz through 26.5 GHz (seeNews from Rohde & Schwarz 142).Operation is possible round theclock, so tests can be conducted faster and are more attractive interms of cost. Another two Rohde &Schwarz EMI test systems (ESH3/ESVP/EZM) have been in operationfor a number of years in three otheranechoic chambers of the institute.The customers are divisions of Sie-mens itself, international industry,state, civil and military bodies.

K. Geigl; D. Poltnigg

First DKD qualification for a mobile calibration labThe Rohde & Schwarz Cologne Planthas received approval from the Phy-sikalisch-Technische Bundesanstalt (PTB, German bureau of standards)to conduct DKD calibration and cer-tification at customers’ premises withthe MKL04 mobile calibration labor-atory. Certificates of the DKD (Ger-man calibration service) have a spe-cial advantage in that they are rec-ognized internationally, without anyfurther verification, when a firm isquality-audited. So the customer canbe sure of traceability to national stan-dards as called for in ISO 9000 ff,EN 45001 and other specifications.This process of qualifying a mobilecalibration laboratory in the Ger-man calibration service broke newground, so the requirements for it wereset down in discussions between thePTB and Rohde & Schwarz. Theywent far beyond the demands madeon a stationary calibration lab ofcourse, and included– measures for maintaining the cali-bration status of the standards and

instruments during transport and on-site operation,– maintenance of the required en-vironmental conditions on site andduring transport,– assurance of calibration of the stan-dards in the superordinate, stationaryDKD calibration laboratory at theRohde & Schwarz Cologne Plant.

In addition, the engineer performingon-site calibration obviously has tobe specially qualified. His workplacein the MKL04 is an air-conditionedcompartment in a van body mount-ed on a truck chassis (photo above).There are four workstations for DC,AC and high-frequency measuredvariables. Calibration on site natu-rally has its benefits for the customercompared to calibration at a station-ary facility. No time is lost for trans-port, and turnaround time is restrict-ed to the duration of calibration.Calibration of Rohde & Schwarzand other brands of equipment issingle source, and visiting a custom-er in this way helps promote goodcontacts. H. Bremmekamp

with application-related backgroundphotos and a brief explanatory text.The logo for the show was “Compe-tence in Avionics and ATC Comms”.A very professional and expert image was created by products selected from test engineering forATC, VHF-UHF ATC communication,traffic control with direction finders,military and civil avionics, mobile airtraffic control and determination ofposition in traffic management withGPS/DGPS.

After experiencing all the moderntechnology, customers and visitorswere able to refresh themselves inthe “Fliegerstüberl”, the centerpieceof the stand and extremely popular.Once again it could be seen that the show is a major event for bothcustomers and exhibitors, and it canonly be hoped that the ILA reallydoes fulfil its promise of becoming asuccess story, especially in its inter-nationalism and as a gateway to theeast. J. Frantzen

ILA 96 – Rohde & Schwarz demonstrates its competenceThe international aerospace show inBerlin from 13 through 19 May 1996was a real attraction this time round.216,000 visitors attended, some44 % more than two years ago. Themain reasons were the interestingexhibits and flight demonstrations of course, like the world première ofEurofighter 2000 and the NH90multi-mission helicopter, and thegood weather also did its share. Thenumber of major international com-panies attending was also higherthis time, even though there is someway to go before the likes of theAérosalon in Le Bourget/Paris canbe matched. But the signs are veryencouraging, and the show’s claimto be a gateway to markets in the eastfor German and international indus-try seems to be bearing first fruit.

Rohde & Schwarz was present on itsown stand in a new design (photobelow). The exhibits were presented

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Newsgrams

Rohde & Schwarz receiversfor British aviation authorityBritain’s CAA (civil aviation au-thority) recently took delivery of 14 Rohde & Schwarz VHF receivers forStansted Airport (right in the photobelow Derek McLauchlan, Chief Executive of NATS, part of the CAA,accepting the first unit from Wolf-gang Winter, Sales Director Europeof Rohde & Schwarz). This is part of a contract won five years ago,during which time more than 1200VHF-UHF transmitters and receivershave already been supplied for theCAA’s communications facilities. Thehigh reliability of the equipment enables CAA technicians to carryout their work efficiently and withoutinterruption. As Paul Bolden, projectmanager of national air-traffic ser-vices, put it: “On average the Rohde& Schwarz equipment is exceed-ing the contracted availability of33,000 hours MTBF by about 60%.This has allowed us to consolidateour maintenance facilities. The mod-ular construction of the equipmentmeans that site engineers now onlyreplace a faulty unit with the spare.The failed unit is then refurbished as required at our central mainte-nance unit before being tested andreturned as the station spare. Previ-ously many faults at component level were repaired on site by the engineer. This has reduced on-sitespares holdings.“ Bolden added: “Adirect benefit of the revised mainte-nance policy is that training require-ments have reduced considerablyand training course duration hasnow been cut by 50 %.”

T. Stephens

Satphone for CARE CanadaThe CARE Canada organization,whose headquarters are in Ottawa,carries out emergency humanitarianrelief operations around the world.So its workers need to be able to bereached at any time and whereverthey are, even in regions with poorinfrastructure, as is often the case.For this reason CARE Canada or-dered SP1600 Inmarsat M satellitetelephones from Rohde & Schwarz.SP1600 provides CARE’s staff withinterference-free communication,greater security and improved effec-tiveness. The digital Inmarsat M stan-

dard using four geostationary satel-lites enables highly mobile, globalcommunication. Speech, data, faxand pictures can be transmitted bydirect distance dialling from justabout anywhere in the world to anysubscriber of the public telephonenetwork (see News from Rohde &Schwarz 145 and 149).

The photo shows Christopher Cush-ing (left), senior program officer ofthe emergency response unit ofCARE Canada, and Peter Foulger,Vice President Sales and Marketingof Rohde & Schwarz Canada, at the handover of an SP1600 satellitetelephone in its briefcase version.

D.G. Stephenson

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On 4 October 1996 Dr. phil. nat.Dr.-Ing. E.h. Lothar Rohde would havebeen 90. He departed from us muchtoo early in 1985. Dr. Rohde was notonly one of the founders of the compa-ny. Until his death he was its technicaland scientific impulse. Dr. Rohde hadan infallible understanding of the chal-lenges posed by a customer’s require-ment and was able to respond withunique solutions. His first principle wasspeedy implementation of the readyproduct for key customers.

He challenged design engineers to goto the limits of what was possible, tech-nically and in how fast they achieved ittoo. His visionary, pace-setting ideas,which he reported on in countless pub-lications all over the world and record-ed in numerous patents, made a deci-sive contribution to Rohde & Schwarz’sworldwide reputation.

His maxims – intuition and care andconcern for the customer – are a modeland legacy for us today in moulding thecompany’s future.

F. Schwarz; H. Wagner

In memoriam Dr. Rohde


Press comments

Bavaria live in ChinaThe »Wirtschaftswoche« of 25 April 1996 report-ed about a DAB demonstration, in which the vice-minister of China’s ministry for broadcasting, filmand technology had an opportunity of gatheringinformation on the status of the DAB project cur-rently under way in Bavaria:

He Dong Cai shook his head in astonishment whenthe car radio announced: “Slow moving traffic onthe circular and arterial roads in and around Munich“. Bavaria live in China. The minister hadheard a warning to drivers sent over the air as partof Bavaria’s DAB (digital audio broadcasting) pro-ject. ...The DAB lobby has a further argument forpotential customers like China: its know-how leadbased on years of experience. The engineers of theMunich-based communications and test engineer-ing specialist Rohde & Schwarz, for instance, havebeen looking into the possibilities of DAB since1985 already. The biggest item on the agenda todate is the pilot project in Bavaria, costing 42 mil-lion DM.

Optical and electrical testThis combination interested number 4/1996 ofthe English magazine »Test«, which looked at theLV1 test system:

The capabilities of LV1 really show through inte-gration in a Rohde & Schwarz production testingsystem. The magic word is parallelization. Thesteps of the electrical test (eg in-circuit test) and theoptical test run entirely in parallel without any timeloss. But it is also possible to combine optical andelectrical tests (eg display test, LEDs), substantiallyenhancing test depth and without the need for extra tools or test time.

Constantly on the move, the mobile units of thenew radiation test squad of the German army,most of whose equipment came from Rohde &Schwarz. In edition 6/1996 of »Soldat und Tech-nik«, a magazine for defence technology, arma-ments and logistics, author Harald Konrad spokeof the job of this service: radiation tests on equip-ment and systems, buildings and rooms, etc.

CE labelling has been in force throughout the EUsince the beginning of the year, and this was atopic for edition 1–2/1996 of the Austrian mag-azine »Elektronik-Schau«. Under the title “EMCprecertification testing for everyone” it presentedEMI Test Receiver ESPC from Rohde & Schwarz asan attractively priced and straightforward test setfor EMC measurements parallel to the productionprocess.

Pinpointing by satelliteElaborate searching for mislaid containers was asubject for the daily »Blick durch die Wirtschaft«on 23 April 1996:

Goods traffic by sea is largely handled with stan-dard containers. Hamburg’s Hafen- und LagerhausAG (HHLA) moves some 1.5 million of these bigboxes every year. ...Mislaid containers can be anightmare when they are not found where theyshould be because of a mistake by the driver.Tracking them down can be a long process, andthe ship has to wait in the meantime. Just one layday costs an average of 100,000 DM. So HHLAasked Rohde & Schwarz to devise a means ofsearching for them. It works by satellite locationwith GPS (global positioning system) and there aretwo versions of it. ...But often it is still not accurateenough. So Rohde & Schwarz then came up withdifferential GPS, increasing accuracy to about onemeter.

Superlative of the superlatives? That was thequestion put by the international magazine forradio »funk« in its June 1996 issue. It not onlymeant the automatic linear shortwave boosterEhorn Alpha 87 A from the US company ETO butalso a spectrum analyzer that is absolutely top inits class, Rohde & Schwarz’s FSEA20, which themagazine’s engineers used for 122 tests to soundout this power amplifier.

Digital Video Component Analyzer VCA servedas an eye catcher for the cover of the April 1996edition of the English monthly magazine »TVB Europe«. VCA combines the conventional testingskills of analog TV waveform monitors with wholenew functions for monitoring digital coding andsignal transmission. It allows in-depth analysis ofdata content and examination of the data frame.


Final article

In the past decades, classic broadcast-ing, namely sound and TV broadcast-ing, used to be a field of its own withspecific developments, largely indepen-dent of the world of telecommunica-tions and computers.

Sound broadcasting

Analog sound broadcasting, using amplitude modulation for longwave,shortwave and mediumwave and fre-quency modulation for VHF, more orless retained its principle of sound trans-mission over the past decades. The on-ly innovation was the radio data system(RDS), which was specified in 1984and then launched in Europe with dif-ferences in the information services pro-vided from country to country. With itsintroduction in the United States as from1994 and in many other non-Europeancountries RDS became worldwide stan-dard.

The compact disc, launched by Sonyand Philips in 1985, was one of theevents triggering off the revolution insound broadcasting towards digitaltechniques. The CD created qualityvery close to that of a concert hall andadded a further benefit in terms of sim-ple and robust handling. The CD wasof course a challenge to sound broad-casting to provide the same quality andperformance features. This is when thedemand for terrestrial propagation ofdigital audio broadcasts for mobile re-ception came up. From 1988 to 1992the specification committee EUREKA147 defined digital sound transmissionwith DAB (digital audio broadcasting)as a pure audio transmission system formobile reception up to a vehicle speedof 160 km/h. Further applications covered by keywords such as “value-added service” and “data service”were added. The DAB channel can beconsidered as transparent point-to-areacoverage for mobile reception and with an effective data capacity of about1.2 Mbit/s. The introduction of DAB

Digital broadcasting and multimedia communication

data burst. An intermediate stage in the overall development is the analogPALplus method, which is compatiblewith PAL but specified for the new aspect ratio 16:9. Digitization in thepicture area began in the TV studio withthe specification of the 4:2:2 componentstandard (CCIR Rec. 601). As for trans-mission from the studio to the viewer,the future lies no doubt in digital videobroadcasting (DVB), which is ready tobe implemented in the media of satel-lite, cable and terrestrial transmissions.Toward the end of 1995, the EuropeanDVB project concluded the specificationof channel coding and modulation forbroadband digital TV channels.

With DVB the digital baseband signalis sent in compressed form according tothe MPEG2 standard (Moving PictureExperts Group). Depending on thecompression factor there are differentquality levels and data rates: LDTV (lim-ited definition TV with 1 to 1.5 Mbit/s),SDTV (standard definition with 4 to 6 Mbit/s), EDTV (enhanced definitionwith 11 Mbit/s), HDTV (high definitionwith 30 Mbit/s). The net data capacityof one or more video and/or audiosources is transmitted within a multiplexsignal (transport stream, TS). DVB thusfollows the container principle with

in Europe and many countries outsideEurope should be completed by the turnof the millennium.

Television

The international TV standards PAL,SECAM and NTSC have practicallybeen untouched up to the present dayas far as the picture information is con-cerned. The developments made mainlyhad a program-supplementary charac-ter. Over the past ten years innovationswere achieved on the basis of the giv-en redundancy in the time- and frequen-cy-related representation of the signal.In the mid-70s, for example, the teletextsystem was launched in different ver-sions throughout Europe. Another digi-tal TV service was added in the early80s: the video program system (VPS)based on the TV data line ensuring pro-gram-synchronous recording by videorecorders even in the event of programdelays.

The change in TV picture transmissioncame about in the mid-80s in Europewith the compatible MAC (multiplex analog component) line. D2MAC is acombination of separately transmitted,compressed luminance and chromi-nance signals and a digital sound and

Satellite reception

Receiver/decoderCable

ISDNTerrestrial reception

Domestic TV receiver

Cassette recorder

Digital video cassetteVideo CD

Video workstation

CD player

FIG 1Scenario for utiliza-

tion of DVB [1]


transparent transmission channels. Er-ror protection for the transport stream isadapted to the physical medium bymeans of channel coding. The stipulat-ed modulation modes are QPSK (quad-rature phase shift keying) for satellitetransmissions, 64QAM (quadratureamplitude modulation) for cable andOFDM (orthogonal frequency divisionand multiplexing) for terrestrial broad-casting. For the latter, the modulator inthe terrestrial transmitter is followed byhigh-power amplifiers for the OFDMmodulation signal. These amplifiers arepreferably of solid-state design and feature high linearity.

Multimedia

Parallel to the revolutionary develop-ments in the field of broadcasting, a union of the worlds of audio/video,telecommunication and computer wasstarted up last year for the consumersector (FIG 1). “Multimedia” is synony-

mous for the convergence of the appli-cations.

In this context the foremost feature is thecombination of devices in the homesuch as desktop workstations, CD video,digital video cassettes, CD playersand/or video cameras to form a kind oflocal area network (LAN). The secondfeature, which is interactivity via adata channel, can nowadays alreadybe implemented via digital telecom-munication media such as GSM/PCN(global system for mobile communi-cations/personal communication net-work), ISDN (integrated services digitalnetwork) or Internet. Multimedia alsoimplies a third feature, ie the broad-band transmission of moving pictures,sound signals and data services. Theclassic broadcasting media using ter-restrial, satellite and cable transmis-sions with SMATV (satellite master an-tenna TV) are utilized in the introducto-ry phase. Further broadcasting media

such as MMDS (multichannel micro-wave distribution system), BISDN(broadband ISDN) or IBCN (integratedbroadband communications network)or ADSL (asymmetrical digital sub-scriber line) are being developed andmade accessible for multimedia trans-mission. The interactivity potential istaken account of by an initially narrow-band back channel in the transmissionmedium.

The new multimedia world needs ac-ceptance by the consumers of course.Therefore it must be introduced step by step. In the first step compatibilitybetween the existing TV receiver andthe new digital transmission technologywill be established with the aid of theset-top box or the integrated receiverdecoder (IRD). The set-top box has functions similar to a computer to establish the connections between thedigital broadcasting medium and theconventional TV receiver, the PC andthe telecommunications network, ie it isa multimedia switching center. Broad-band transmission channels for multi-media are specified in the form of DABand DVB-S (satellite), DVB-C (cable)and DVB-T (terrestrial) and their imple-

Final article

FIG 3 MPEG2 Generator DVG and Measure-ment Decoder DVMD for DVB transport datastreams [3]

FIG 2CATV configurationwith QAM modulator for intelligent broad-band communicationsystems [2]


mentation is already in progress insome European countries.

The new digital transmission technol-ogies bring decisive benefits for theconsumer:• low-cost receivers in a multimedia

environment,• good picture quality (SDTV) to high

definition TV,• large number of programs,• portable reception of terrestrial TV

programs,as well as for the network operator:• economical utilization of the resource

frequency,• flexible use of the transmission chan-

nel,• reduction of investment, energy and

service costs.

Therefore the implementation of theDAB and DVB standards is beingstrongly pushed ahead as shown bythe following examples.

Implementation of DAB began in1995 with the Bavarian pilot project asthe first project worldwide using single-frequency operation on this scale. Inaddition to the channel-12 transmittersincluding DAB coder/decoder, Rohde& Schwarz supplied the complete infra-structure with audio baseband coding(MUSIC) and DAB multiplexer as wellas program distribution via satellite.German Telekom recently started com-missioning 60 DAB L-band transmittersfor a national coverage network withRohde & Schwarz as the main supplier.

Digital video broadcasting was start-ed in mid-1996 via the SES-ASTRA satellite 1F, which was launched to itsorbital position 19.2° east from the Baikonur (Kazakhstan) cosmodrome inApril 1996. Another two ASTRA digi-tal satellites are planned for 1997. Eutelsat, too, will take up digital tele-vision in 1997 via the Hot Bird satellites4 and 5.

Broadband cable technology is optimally prepared for digital televisionwith interactive communication: the

hyperband originally intended for D2MAC transmission is now available.In addition, interactive capability in theform of the back channel is given in the range from 5 to 20 MHz. GermanTelekom will have equipped its cableheadends with modern digital systemsfor 64QAM modulation, frequencyconversion and distribution by the endof 1996 and relies on well-proven Rohde & Schwarz technology (FIG 2).The next step will be the implementation

be continued in the new digital technol-ogy. We offer solutions in the form ofunits, systems, turnkey single-frequencynetworks, broadband communicationsystems as well as remotely controlledtest and monitoring equipment for net-work operators. With its key productsfor digital broadcasting system and testequipment (FIG 3 and 4), Rohde &Schwarz is right now best prepared tolive up to its reputation as one of theworld’s leading DAB/DVB suppliers

Final article

and to master the quantum leap into thedigital future of broadcasting and multi-media communication.

Paul Dambacher

REFERENCES

[1] Reimers, U.: Digitale Fernsehtechnik, Daten-kompression und Übertragung für DVB.Springer Verlag (1995)

[2] Schönberger, P.; Sturm, P.; Scheide, R.: CATVHeadend System CT200 – CATV signal pro-cessing intelligent, compact, versatile. Newsfrom Rohde & Schwarz (1995), No. 148, pp 23 – 25

[3] Fischbacher, M.; Weigold, H.: MPEG2 Gen-erator DVG and MPEG2 Measurement De-coder DVMD – Test equipment for digital TVin line with MPEG2. In this issue, pp 20 – 23

[4] Balz, C.; Polz, E.; Fischer, W.: TV Test Receiv-er Family EFA – Top fit for digital television.In this issue, pp 17 –19

of intelligent interactive headends withservers, billing and network monitoringas well as connection to public datanetworks.

Terrestrial digital video broadcastingwill be started in the UK in 1997 withthe programs of NTL and BBC. In Germany, DVB-T pilot projects in Berlin,Cologne and Munich are now in theplanning stage. Since 1995, a DVB-Ttransmitter from Rohde & Schwarz has been tested by the Swiss PTT. Thistransmitter can be switched over to theemission of PAL signals for coveragecomparisons.

The particular strength of Rohde &Schwarz in analog broadcasting will

FIG 4 TV Test Receiver EFA with QAM measure-ment functions for DVB-C [4]

ROHDE& SCHWARZ GmbH & Co. KG · Mühldorfstraße 15 · D-81671 MünchenP. O. B. 8014 69 · D-81614 München · Tel. (+49 89) 41 29-0 · Fax (+49 89) 41 29-21 64

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