ss 200: required for system upgrades · the ss 200 has a jack for 12 vdc power; a 12 vdc supply can...

M A R C H / A P R I L 1 9 9 9 V O L U M E 1 0 N U M B E R 2

VSC 200D & VSC 300D Scan Converters Digital Output for the Nonlinear World

(continued on page 2– See “SS 200”)

Many of the existing boardrooms thatwere built in the past ten years haveAV systems that are CRT based.Currently, AV dealers are servicingand upgrading these installations—often replacing the older CRT projec-tors with new digital displays(LCD/DLP/Plasma). These upgradespresent a challenge, in that the oldCRT installations were often fourwire (RGBS) while digital displaydevices usually require five wire(RGBHV) for proper operation.

RGBS is usually created by taking aRGBHV signal and using an XOR(exclusive OR) type gate to combinethe horizontal and vertical syncsignals into one composite syncsignal. In the interfacing industry, thisis a common and reliable way of

Nonlinear editing is fastbecoming the preferredmeans of progress for manyproduction and broadcaststudios. With the ability toflex at a moment’s notice,drag shots from the end of asegment to the beginning and backagain instantaneously, and blast outmultiple versions of a project, it’s nowonder nonlinear is considered sorevolutionary.

The departure from analog to linear(digital) technology in the broadcastenvironment has changed much of theway the media production industryworks. Production companies areforegoing the analog way of tape-

Tweeker Use ....................................................3Manufacturing Free Education ..........................4Comb Filters—Part 3..........................................5New Products....................................................6Unique Techniques: St. Joseph’s University..........8Introduction to Cookies....................................11Tech Corner: ADSP™ ......................................12New News ......................................................14Web Tip ..........................................................16

SS 200:Required for System Upgrades

(continued on page 3– See “VSC 200D”)

In This Issue:

combining sync. However, this process may produce a syncsignal that is incompatible with digital display devices. Usingan XOR gate to combine H&V sync causes the horizontalsync pulse to be incorrectly positioned during the verticalinterval. The horizontal sync pulse loses its proper timingrelationship. Once this occurs, it is not easy to break out theseparate H&V sync again and restore proper timing. Thevideo signal produced by creating a RGBHV signal from aRGBS signal will most likely have incorrect sync timing.Such a signal produces an unstable or distorted image on

EXTRON’S VSC 200D

E X T R O N E W S M A R / A P R 1 9 9 9

2

ExtroNews™

Managing Editor: Amy KramerTechnical Editors: Jim Scrivner, Roger McCarten, Pat Charlton

Graphic Designers: Carol Hubben, Jill Streit, Cyme Azar

Tech Writers: Bill Field, June Lee

President: Andrew EdwardsV.P., Finance: Ed Ellingwood

V.P., Operations: Bob NicholsV.P., Product Development: Dave Pincek

V.P., R&D: Brian TaraciV.P., Engineering: Steve Somers

V.P., Human Resources: Joanne GrushV.P., Information Technologies: Ivan Perez

National Sales Managers:Jeff Gibson, Mandi Speer

Int’l Sales Manager: Geoff Abbott

We welcome your comments andcontributions! Please submit ideas to

Amy Kramer • 714.491.1500

Volume 10, Number 2 Mar/Apr, 1999ExtroNews is published by ExtronElectronics/ RGB Systems Inc. 1230 SouthLewis Street, Anaheim, CA 92805. Allrights reserved. No portion of thisnewsletter may be reproduced in any formwithout written permission from the man-aging editor of Extron Electronics’ExtroNews. Every effort has been made toensure accuracy in content; however,Extron assumes no responsibility for errorsand omissions in the information providedherein. ExtroNews is sent free of charge tocommunication industry professionals andend-users. Send address changes,requests for copies, and editorial corre-spondence to: Marketing Dept., ExtronElectronics, at the address above, or call714.491.1500; FAX 714.491.1978. Printedin the United States of America.

digital display devices. Usually this appearsas bending or tearing at the top of the screen.

To solve this problem Extron introduces anew product this year at NAB: the SS 200sync stabilizer. The SS 200 uses Extron'sexclusive ADSP™ (Advanced DigitalSync Processing) technology to restoreproper sync timing. (See ADSP article onpage 12) The SS 200 accepts any qualityRGBS or RGsB signals, and utilizing amethod exclusive to Extron, digitallygenerates a true separate H & V signalwith proper timing. The result will be aclean and stable image on digital displaydevices.

The SS 200 comes with a mounting bracket,which allows the SS 200 to be attached toa projector mount. The diagram belowdepicts how the SS 200 mounting bracketswork. The mounting bracket is detach-able, so the SS 200 can be installed in anumber of ways. Optional brackets areavailable for horizontal (under desk) or

vertical (through desk) mounting.

The SS 200 will accept RGBHV, RGBS,RGsB (sync on green will be automati-cally stripped) or RsGsBs signals. Theinput connection consists of five femaleBNCs. Output can be either RGBHV orRGBS—switch selectable. The outputsignal is available simultaneously on twooutput connectors, a female VGAconnector and on five female BNCs. Thisprovides the user with a choice of outputconnectors, possibly eliminating the needfor an adapter cable. The extra output canalso be used for a local monitor connec-tion or preview monitor, if required.

The SS 200 features DIP switches thatallow the user to enable/disable the hori-zontal shift adjustment, turn the verticalcorrection on or off, enable/disableserration pulses, select between 75 or 510ohm sync termination, set the syncpolarity, and select between separateH&V or composite sync output.

Ceiling

5 BNCInput

SS 200

MountingBolt

ProjectorMountingBracket

VGA / 5 BNCOutput ToProjector

SS 200– continued from page 1

The SS 200 has a jack for 12 VDC power; a12 VDC supply can be found on someprojectors. The SS 200 comes with a detach-able 100–240 VAC power supply.

The SS 200 (PN: 60-285-01) lists for$695.00 (US Dollars). For more informationabout the SS 200, please call your localExtron representative at: 714.491.1500(Extron USA); +31.33.453.4040 (ExtronEurope); or +65.226.0015 (Extron Asia). Or visit our website: http://www.extron.com/product/ss200.stm.


3

Michael Creley with Communitronics Corporation of St. Louis, Missouri

has won this issue’s tweeker contest with his entry called

"Whatever the product, you'll always hit the bullseye with Extron"

Send us your photograph ofhow you use the Tweeker. If

we publish it in a future issueof ExtroNews, we’ll give you

a free VTG 150.

Send entries (along with your explanation)

to: Extron Tweeker Contest1230 S. Lewis StreetAnaheim, CA 92805

based editing systems in favor ofdigital/PC based technology. The majoradvantages of these new editing systemsare they maintain the integrity of thedigital video signal by capitalizing oncomputer generated video and canproduce results quickly saving both timeand money.

4:2:2 SERIAL DIGITAL OUTPUTExtron has kept up with the changes intechnology by introducing two productsthat provide additional support for theproduction and broadcast environments.In a world of digital transmission main-taining the digital signal is significant tothe overall quality of the final image.Continuous conversion between analogand digital formats ultimately degradesthe signal. That is why it is advantageousto use devices that provide a digitaloutput in a production system design.

Extron’s VSC 200D and 300D video scanconverters provide 4:2:2 serial digitaloutput for connecting to D-1 decks ordigital video editing stations. Going fromdigital video into a digital editing systemmakes it easy to feed in a clean signal,manipulate it and take it back out fordirect broadcast, videotaping or DVDmastering. For example, video clips engi-neered on an SGI visual workstation canbe transported in real time to a nonlinearediting system via the VSC 200D or300D.

BROADCAST STANDARDS: RS-170A & VIDEO OVERLAY The VSC 200D and 300D provide highquality component output for use inproduction and broadcast settings.Computer-generated signals are convertedto composite or S-video signals for NTSCor PAL. The NTSC and PAL output onthese scan converters complies with thebroadcast quality RS-170A standard.

VSC 200D & VSC 300D– continued from page 1

RS-232 Control

LCD Projector

BetacamTape Deck

VideoconferencingSystem

VCR

Video Monitor

ExternalGenlockTiming

VSC 300D

CompositeVideo

S-video

or

or

MAC InputVGA Input

or or

Sun/SGI Input

OUT

OUTPUTS

VGA

MAC

INPUT/LOOP OUT

VGA OUT

50/60 Hz 0.5A

100-240

Hi Carol

Hi Carol

(continued on page 10–See “VSC 200D & 300D”)


4

JEFF GIBSON

Manufacturing Free Educationby Jeff Gibson, National Sales Manager

Q: What product does Extron manu-facture that has no input connec-tors, no output connectors, doesn’tcome in a box and sells for thereasonably low price of $0.00?

A: The answer is education.

That’s right, Extron manufacturessomething that, in this case, moneycan’t buy: it’s education. And theresults are classes filled to capacity.

Extron School was formed to educatethe A/V industry in the technicalsubjects where Extron is recognized ashaving the knowledge. Students spendtwo full days with some of theindustry’s best trainers, as well asfellow colleagues, discussing thetheories behind specific technologiesand then utilizing their newfoundknowledge in a hands-on environment.

The school has been so popular thatsince 1997, Extron has taken their theschool on the road. Dealers who areunable to come to the Anaheim, CA,office have the opportunity to attendExtron School on the Road in theirown backyard. The idea provedpopular from the onset. There isalways a waiting list of students eagerto gain the knowledge Extronprovides.

So, what does this free educationmean to A/V professionals? A.V.Associates’ senior engineer, FrankGrillo, explains: “For me, the ExtronTraining Classes are the best in the

industry. Extron has always set thestandard of quality for their products.This same standard is apparent intheir product and training literature,as well as their staff of instructors.The talented instructors are extremelywell prepared, informative and enter-taining.” Grillo concluded, “Theirdemonstrations not only emphasizethe lessons, but they make each onefun . . . I was never bored!Presentation professionals needpresentation professionals likeExtron.”

After attending a session of ExtronSchool on the Road, Captain GregMcMillion, United States Air Force,commented: “This is without doubtthe best course I have participated induring my thirteen years of govern-ment service. The instructors are ofthe highest quality, [and] the classesare both interesting and educa-tional—the Extron personnel ingeneral are just superb. The produc-tion and execution of the school is amodel for other manufacturers tofollow. I am very impressed—[Extron] could teach the military afew things in the set-up and presenta-tion arena.”

Universities and trade schools justdon’t cover everything A/V profes-sionals need to know. Topics such asAdvanced Interfacing, Bandwidth,System Switching, Matrix Switching,RS-232 & RS-422, DesigningSystems, and Display Technologiesare not covered extensively enough inthe course curriculum. To besuccessful in this industry, having in-depth knowledge is a must. The valueof information is obvious as thedemand for education continues togrow and grow, and the positive

results are evident in the careers ofpast Extron students.

From the beginning, Extron hasremained committed to supportingdealers and consultants in ourindustry. Education and training issimply a part of Extron’s culture.In addition to Extron School andExtron School on the Road, Extronprovides instructors and educa-tional programs for ICIA’s Schools,INFOCOMM International®,NSCA, CEDIA and almost anyplace where industry seminars areheld.

Whether our solutions come in abox or are taught in a classroom,we are committed to providing theindustry with the best that tech-nology has to offer.

Jeff Gibson is a National SalesManager at Extron Electronics.

Inquiries concerning Extron Schooland Extron School on the Road canbe directed to Extron by calling 1-800-633-9876 or visiting our website at: http://www.extron.com/school/index.html.


5

STEVE SOMERS

Comb Filters: NTSC Decoding Basicsby Steve Somers, V.P. Engineering

Line Comb Filter Decoders(Part 3)

I’d like to thank all of you for yourcomplimentary input on my articlesand their value to you. Here in Part 3,we will move forward into the appli-cation of the comb filter in NTSCdecoding. And, in case you have notread parts one and two, I want to rein-troduce the basic NTSC decodingsystem diagram as Figure 1. The Y/CSeparator portion continues to be thereal focus of this series as thisfunction is the most critical in thesystem.

I previously covered operation of theNotch/Bandpass Filter. Recall thattwo simple, passive type filters (ofcourse, there are active variants butthey accomplish the same function)are used to perform simple separationof luma information and chromainformation in the frequency domain.Since this type of filter cannot tell thedifference between one frequency andanother with respect to time, someluma information spills into thechroma channel and vice versa.Therefore, it’s hardly an ideal systembut it is low in cost and providesacceptable performance (perhaps upto 250 lines of horizontal resolution)for mass production purposes.

Since the beginning of professionaltelevision broadcast, the TV industryhas looked for an affordable method

to separate luma from chroma moreefficiently. It took about twenty yearsafter the introduction of color televisionbefore reasonably affordable combfilter methods were realized. And, forthe most part, those methods wereanalog in their earliest implementations.Today, digital processing is the normfor comb filters and the technicalintrigue continues as we inch closer tothe full digital television age.

Regardless of the specific componentsused to implement the “combingprocess”, we are going to look at thebasic topologies currently in use andunderstand the relative advantages ofeach. Lowest in the food chain is thesingle line comb filter; next, the 2-linecomb filter; and yes, the 3-line version;replaced by 2D adaptive methods; and,

(continued on page 18– See “Comb Filters”)

currently the sophisticated 3D motion-adaptive comb filter. All comb filtertopologies share an importantconcept…picture information is aboutthe same from line to line.Fundamentally, incoming informationis stored in some way; then comparedto successive information in such away as to attempt cancellation (in thetime domain) of luma information fromthe chroma channel and, vice versa.Crystal clear, right?

OK, FORM ONE OR TWO LINESThe earliest and simplest versions of acomb filter delayed one horizontal lineof picture information and compared itto the current line passing through the

Y/CSEPARATOR

DELAY

COLORDIFFERENCE

DECODER

MATRIXDECODER

Y YR

G

B

R - Y

B - Y

NTSCCOMPOSITE

VIDEO

C

COLOR BURST 3.58MHzOSC

FIGURE 1. NTSC DECODING SYSTEM


6

CVC 200 Video ConverterYou need to display your HDTV 720p or1080i source, but your display device onlyhas a RGBHV input. What do you do?Use Extron's CVC 200, a universal high-resolution component or HDTV video toRGBS or RGBHV converter. The CVC 200offers two distinct advantages over theCVC 100—HDTV 720p and HDTV 1080icapabilities. The CVC 200 converts theHDTV rates: 720p, 1080i, and SMPTE 240to RGBS or RGBHV. The CVC 200 alsoconverts Betacam, component video,Professional component video, and W-VHS to RGBS or RGBHV.

The CVC 200 enables the display ofHDTV and component video images onRGB monitors and projectors. Other appli-cations include converting computer videofrom DVD sources to analog RGB signalsfor displaying DVD images on RGB

S-Video to BNCAdapterExtron’s S-video to BNC Adapter is nowmore convenient to use. The male BNCconnectors have been replaced with femaleBNC crimp connectors, eliminating theneed for barrel connectors when you use anextension cable. With a molded, gold-plated S-video connector, along withExtron’s new BNC strain reliefs, thisadapter maintains its professional appear-ance while providing added functionality.The S-video to BNC adapter (PN: 26-353-01) lists for $35.00 (US Dollars). For moreinformation, please call your local Extronrepresentative at: 714.491.1500 (ExtronUSA); +31.33.453.4040 (Extron Europe); or +65.226.0015 (Extron Asia). Or visit our website: http://www.extron.com/product/miscadapter.stm

projection screens. The rack-mountableCVC 200 is easy-to-use and features BNCconnectors for its inputs and outputs. Itincludes a 100-240 VAC, 50/60 Hz,internal power supply.

The CVC 200 (PN: 60-284-01) lists for$895.00. (US Dollars) For more informationabout the CVC 200, please call your localExtron representative at: 714.491.1500(Extron USA); +31.33.453.4040 (ExtronEurope); or +65.226.0015 (Extron Asia). Or visit our website:http://www.extron.com/product/cvc200.stm.

The rough handling that cables aresubjected to in a typical A/V environmentcan cause significant damage, resulting inpoor or inconsistent video reliabilityandperformance. The point at which thecable terminates to the connector is mostvulnerable. But with BNC strain reliefslessening the pressure, your cables are lesslikely to be damaged.

Extron’s new BNC strain reliefs arereplacing the heat shrinks on these Extronproducts: the S-Video to BNC adapter, alladapters using BNC mini-HR male connec-tors, and the pre-cut lengths of the BNC-4HR, BNC-5 HR, and BNC-5 HR Plenumcables. BNC strain reliefs have a profes-sional, sleek design, adding a finished lookto your cabling, and they are available insix different colors: red, green, blue, black,yellow, and white.

BNC strain reliefs and heat shrinks areavailable separately as accessory items forbulk cable assembly. For more information,please call your local Extron representative at:714.491.1500 (Extron USA); +31.33.453.4040(Extron Europe); or +65.226.0015 (ExtronAsia).

BNC Strain Reliefs

CVC 200: REPLACES THE CVC 100


7

Imagine this scenario: you need to add an S-VHS VCR source to your installation withRGBHV projectors and computer sources,but you want to remain consistent with yourfive-wire switching and distribution. Whatto do? Consider Extron’s CD 800, a profes-sional-quality quad-standard video decoderused to convert NTSC 3.58, NTSC 4.43,SECAM, and PAL composite video or S-Video into RGsB, RGBS, or RGBHV.

Using an improved decoder chip, with athree-line adaptive comb filter, the CD 800virtually eliminates chroma noise andenables a projector or monitor to display ahigher quality image than that of compositevideo or S-video. Applications includedisplaying video signals on RGB monitorsand the routing of video through RGBswitching and distribution systems.

The CD 800 provides a single BNC forcomposite video input and a 4-pin mini-DINconnector for S-video input. Inputs are

selectable by auto-switch, front panelbuttons, RS-232, or contact closure. The CD 800 outputs analog RGB on BNCs witha choice of composite sync, SOG, orseparate H&V sync. For optimizing imagequality, the CD 800 provides these picturecontrols: color, tint, contrast, and horizontalshift. The controls’ settings are automati-cally saved for each of the two inputs. TheCD 800 offers these additional features:auto-switch enable/disable, serration pulseremoval enable/disable, and selection ofhorizontal and vertical sync polarities. TheCD 800 includes a 100-240 VAC, 50/60 Hzinternal power supply.

The CD 800 (PN: 60-267-01) lists for$1595.00 (US Dollars). For more informa-tion, please call your local Extron represen-tative at: 714.491.1500 (Extron USA);+31.33.453.4040 (Extron Europe); or+65.226.0015 (Extron Asia). Or visit our website:http://www.extron.com/product/cd800.stm.

VCR Laser Disk PlayerLarge ScreenRear Projector

RS-232 Control

LCD Projector

Video Monitor

OUTPUT

RS-232

or

orCD 800

Hi Carol

Hi Carol

VGA Cable with AudioAre you running computer audio along withyour video signal? Chances are, yes. Nowyou can do this with Extron’s convenientVGA Cable with audio. Available invarious lengths, the cable uses high-resolu-tion mini-coaxial cable with a 15-pin HDmale connector and a 24" audio cable witha stereo mini 3.5 mm connector on eachend. The VGA Cable with Audio is ideal fordirect connection of audio and video signalsfrom laptop computers to the System 5cr orLCD projectors.

Various lengths are available. For moreinformation, please call your local Extronrepresentative at: 714.491.1500 (ExtronUSA); +31.33.453.4040 (Extron Europe);or +65.226.0015 (Extron Asia). Or visit ourwebsite: http://www.extron.com/product/cable.stm

CD 800Digital Quad-Standard Decoder


8

Unique Techniques:St. Joseph’s University leads the pack in innovative uses of A/V technology

For those who haven’t noticed, colleges anduniversities have been making great stridesin the use of high tech audio/videoequipment for communications and instruc-tional purposes. Rapidly leaving us are thedays when a student would wheel around aspaghetti-wired cart with a VCR and mid-sized television, or perhaps a film-reelprojector. Now, fixed data and graphicsprojectors using high-quality film screensare the rage, along with computer-videointerfacing, shared media sources, central-ized control systems, and dedicated A/Vstaffs to keep it all running. Among theleaders in this trend is St. Joseph’sUniversity in Philadelphia, whose newly-built Mandeville Hall showcases cutting-edge A/V technology like few institutionsof higher education, if any, ever havebefore. Of course, Extron products arethere.

Mandeville Hall is the culmination of thefaculty’s desire for the school to benefitfrom new technology and the systemdesigner’s knowledge of that technology.Reverend Nicholas Rashford, president ofSt. Joseph’s, explains the school’s stand-point: “Overall, what we wanted to do wasto create a traditional classroom environ-ment, but one that would cut a path for thenext millennium, with the technology in thebackground, but enhancing the experienceincredibly.”

To turn this vision into reality, RJCDesigns, Inc. of Glen Burnie, MD werecontracted. Rich Coluzzi, president of RJCexplains: “Father Rashford’s vision asconveyed was to utilize the latest in tech-nology that would give the universitymaximum flexibility in use, fulfill instruc-tional-use criteria, allow for variouscommunications paths, and be as intuitiveto use as possible.” RJC was given a widedegree of latitude in how they fulfilledthese goals, including all of the product andtechnology integration choices.

INFRASTRUCTUREMandeville Hall was designed to havemedia sources centralized for global usagein addition to local sources in specificrooms. To accomplish this, two things werenecessary. First, nearly every room in thebuilding was wired with multiple runs ofaudio, video, and broadband cabling.Second, a master control room was built inan adjacent building that is closer to theuniversity’s pre-existing data processinghub than Mandeville itself. It is here that allexternal communications paths are found,including a satellite link, RF, ISDN lines,etc. Master control’s media sources includelaserdisk, DVD, tuners, video teleconfer-encing codecs, and various types of VCRs.Communications between buildings aredone over fiber, which is converted toanalog at several points in Mandeville. Thisarrangement not only allows for resourcesharing to nearly every room in Mandeville,but control of all systems both locally andfrom master control using AMX controlsystems.

KEY POINTS OF INTERESTDue to space constraints, we cannot look ateverything Mandeville Hall has to offer inthis issue, and we will have to limit ourreview to just two out of the dozens ofareas that contain cutting edge A/V tech-nology. These two areas are among thoseRJC, their contractors (Peirce-Phelps,Vistacom), and the university are the mostproud of, and are also among the mostimpressive in terms of versatility and theuses of technology therein.

MOOT BOARDROOMSThe room layout of each of the two MootBoardrooms (Moot, as in controversial ordebatable) is two tiers of elevated galleryseating in a “U” shape surrounding aboardroom-style table in the center of theroom. The goal was a setting where a boardcould stage debates, while students couldobserve or comment from the galleryseating. Also in the focus area is a 120"DaLite screen for use with a Hughes-JVCmodel 100 projector.

RIGHT:Using Extron’s RGB 320

System, every studentseated in the Moot

Boardroom may route display data from their

laptop computers onto theprojection system. All at

the touch of a button.

LEFT: Mandeville Hall’sTeletorium (short forteleconferencing auditorium) is just oneof many venues thatshowcase advancedaudio/video technologyat St. Joseph’sUniversity.


9

Each of the 36 gallery seats is equippedwith a LAN connection for laptopcomputers, and every other seat has aCrown microphone. What really sets theserooms apart, however, is the Extron RGB320 computer-video interface system. Eachseat has an RGB 324 interface buffer,which converts a laptop’s external videooutput to RGBHV and routes it to an RGB320 interface switcher in the Moots’ obser-vation room. By pressing the “Show Me”button on an RGB 324, each occupant mayroute video and audio from their laptop tothe room’s projection and audio systems.

This system has been used by the businessstudents within Mandeville to display andcompare materials, and other groups haveused it to display evidence during debates.Regardless of the topic at hand, making useof Extron’s RGB 320 interface buffersystem in this way facilitates a more conve-nient way to exchange ideas visually thanpreviously possible.

MOOT OBSERVATION AND LOCAL CONTROLBetween the Moots are the observation andlocal control rooms. The observation roomallows observers to view ongoing activity in

either Moot via windows on either side ofthe room, or by video routed to a pair of40" Pioneer plasma displays. Located inthis room are the 14 Extron RGB 320interface switchers required to control RGB324 interface buffers found in the Moots.When the aforementioned “Show Me”button is selected on one of the buffers, thedisplay signal of an attached laptop is sentthrough the buffer to one of the RGB 320s(each can control six buffers), through oneof two Extron CrossPoint 84HVA matrixswitchers, and on to its routed destination.

The local control room also found hereholds all video production equipment usedwhen recording events within the Moots.Among the equipment found therein is aPanasonic video production switcher,Biamp mixers, and an Extron scanconverter for incorporating computer videointo recordings.

THE MULTIPOINT DISTANCE LEARNING CLASSROOMThe DLC was designed to handle a varietyof conferencing modes, including audioonly, one-way video and two way audio(which nearly every room in Mandeville is

capable of), standard point-to-point videoteleconferencing, and multipoint video tele-conferencing with as many as four remotesites. The room also is designed to incorpo-rate computer-generated video into aconference.

To allow for four remote sites to be viewedsimultaneously and by the entire room, fourToshiba 50" monitor cubes were recessedinto the room’s front. For conferencing witha single site and other display needs, aHughes G1000 projector with a 120"Draper screen was chosen. When in use, thescreen and projector would lower out of theceiling with the screen positioned betweentwo of the monitors.

While the monitors and the Hughesprojector took care of the student viewingneeds at the local end, it was determinedthat this arrangement posed some problemswhen used in the distance learning role,especially for the instructor. One could notface the local audience and theParkerVision auto-tracking camera at therear of the room while viewing the remotesite feed displayed at the front of the room.To solve this problem, an additional displayfor the instructor was necessary. To fill thisrole, a Panasonic projector with a 52"Draper screen was positioned at the rear ofthe room. This “heads-up” display is linedup with the instructor’s camera, allowingone to look at the audience as well as thecamera, and still maintain the illusion ofeye contact with the remote site.

As in every room, size, flexibility andlayout were all taken into considerationwhen designing the instructor’s worksta-tion. With the DLC’s, two side by side IBMcolor LCD monitors were used to accom-modate the AMX PCTouch system and theRIGHT:

A laptop attached to an RGB 324interface buffer. The RGB 320 System

allows students to share data in ways not previously possible.

(continued on page 19—See “St. Joeseph’s Install”)

LEFT: Fourteen Extron RGB 320sand two CrossPoint 84HVAmatrix switchers control theMoot Boardrooms’ 82 RGB 324buffers.


10

VSC 200D & 300D–continued from page 3

The VSC 200D and 300D also providebroadcast quality synchronization withother video devices for the purpose ofpixel switching and chroma keying ofcomputer overlays. A good example ofthis is a broadcast weather segment wherepictures of weather maps are inserted“behind” the weatherman. The segment isactually a composition of a blue back-ground, computer-generated graphics anda camera feed of the talent.

Pixel switching, or chroma keying, refersto the process of creating a neutral back-ground plate (blue or magenta). On thatbackground plate, video images (i.e.,computer generated graphics or videoclips) are superimposed on the neutralcolor. The camera then feeds in the videoof the weatherman talking, laughing andpointing. All of these signals areprocessed to create what you see on yourTV. In order for this to work properly, theoverlay procedure requires studiogenlocking. The VSC 200D/300D areable to genlock to other video devicesignals for purposes of computer overlayas necessary in the production andbroadcast settings.

PRICING AND PROFESSIONAL FEATURESConsidering that Extron’s VSC 200D and300D are professional video scanconverters compatible with professionalbroadcast video systems, you might expectthem to be priced right along with otherwell established video scan converters.However, these products are extremelyreasonable. At $4,995 for the VSC 200Dand $7,745 for the VSC 300D these scanconverters make a great argument forputting one in every editing suite.

Both products are autoscanning so theyautomatically recognize and convert allcomputer signals that fall into thefollowing ranges: VSC 200D—1280x1024 at scan rates of 81 kHz hori-zontal and 120 Hz vertical; VSC 300D—1600x1280 at scan rates of 100 kHz hori-zontal and 120 Hz vertical. They arecompatible with VGA and Mac signalsand allow you to display video images onthe local monitor and display devicesimultaneously.

The VSC 200D and 300D offer severallevels of vertical and horizontal filtering.These filters reduce picture jitter, stabilize

the image and assure that no picture detailis dropped during scan conversion. Theyprovide advanced pixel clocking for greaterpicture detail so that when you zoom in theimage retains its sharpness. Both productsalso provide horizontal and vertical controlsfor greater pan and zoom flexibility.

VSC 300D’S SCALABLE OUTPUTThe VSC 300D additionally featuresscalable output allowing it to scale downhigher resolutions to lower display resolu-tions. For example, the VSC 300D canconvert a computer signal with a resolu-tion of 1600x1280 to a resolution of640x480. Many digital display devicessuch as VGA/SVGA monitors and LCD,DLP or Plasma can only accept signalswithin the 640x480 to 1024x768 ranges.This down conversion is essential todisplaying workstation-generated videoon these types of displays.

All in all, the VSC 200D and 300D areaffordable options for the broadcast andproduction studio environments. Withmany broadcast-type qualities and manyother professional features Extron’s VSCsare perfect for all types of applications.

EXTRON’S VSC 300D


11

Along with the release of our next-generation website this spring, Extronwill begin to implement the use of“cookies.” This brief—and admittedlysimplified—explanation aims to shed alittle light on cookies and dispel someof the prevalent myths surroundingthem.

SO WHAT IS A ‘COOKIE’?In order to understand what a cookie is,it is important to understand a fewthings about the basic nature of theWorld Wide Web. Simply put, websiteshave very short memories. There’s noinherent way to remember even themost rudimentary information about avisitor at any given time. The Webserver’s basic purpose in life is essen-tially to feed a page to anyone who asksfor it, serving visitor after visitor withno regard for what happens afterwards,much like the person behind the counterat a typical cafeteria. This type of trans-action is referred to as a “statelessconnection” in Web parlance.

But what if you want the lady in thehairnet to remember that you preferstuffing to mashed potatoes? The Webserver (and our spud server) have nobuilt-in way of keeping track of suchinformation.

“Cookies” allow the Web server toremember information as a visitormoves from page to page in a website.All a cookie consists of is a very smalltext file (a few bytes, usually) thatresides in a special directory on yourhard drive. The Web browser keeps allof the cookies it receives and uses thisinformation later when the server needsit. You’ll never have to eat potato flakesagain.

WHY USE COOKIES?As Extron begins to provide more user-sensitive information—informationdisplayed based upon the user’s prefer-ences and characteristics—the need toremember basic information about a userbecomes important. Storing simple infor-mation such as a unique ID and passwordin a cookie will allow us to tailor informa-tion to the user, be it articles based uponuser-entered preferences, order-tracking oraccount information. Without imple-menting cookies, Extron won’t be able toprovide these services on our website.

WHY COOKIES AREN’T ANOTHER INCARNATION OF ‘BIG BROTHER’As you can see, cookies are powerful toolsthat allow websites to do much more thandisplay information one page at a time. So,by now you’re probably wondering exactlyhow powerful they are. Do they, forinstance, let anyone’s website track infor-mation about your disdain for mashedpotatoes? Or, perhaps, give Bill Gates abird’s-eye view of the goings-on inside yourcomputer?

Simply put: No. Cookies come with somebuilt-in security features that safeguardagainst such nefarious activities:

• Once a cookie has been placed on yourcomputer it is associated with the domain(for example, www.extron.com) thatcreated it and only pages from thatdomain can access the information insidethe cookie.

• Furthermore, in the rare case that a cookiecontains any sensitive information, it canbe encrypted or scrambled so that—evenif you were to look at it in a text editorlike Notepad—it would be essentiallyuseless to anything or anyone except thedomain to which it belongs.

• Cookies have expiration dates. Thismeans that after a preset time hascome and gone, the cookie isdeleted.

• Your Web browser can be set up tonotify you of any cookies that arebeing set on your computer. Theycan also be configured to rejectcookies all together.

These types of security features makecookies a safe way to store informa-tion on the user’s machine for lateruse. In addition to these built-infeatures, it is worth noting thatExtron Electronics will not store anysensitive information in cookies. Inmost cases, they will be used to storea unique ID and nothing more. Whileyou may certainly decide to rejectany cookies sent to you from our site,we strongly advise against doing this.Simply put, if you disable cookies,you won’t be able to take advantageof some of the new features on oursite.

Despite the sinister rumors that mayhave caught your attention, cookiesare, in fact, quite harmless. Theyprovide a useful mechanism that willcontinue to make our website“smarter,” and provide a valuabletool for customers.

An Introduction to Cookiesby Andrew Todd,Senior Web Developer


12

ADSP™: Interfacingwith Stabilityby Roger McCarten,Product Manager

Extron originally released ADSP™(Advanced Digital SyncProcessing) three years ago whenthe RGB 202xi interface was intro-duced. Due to ADSP™, the RGB202xi has become the preferredinterface for digital displays. SinceADSP™ cleans up and stabilizesthe synchronization signals, itprevents many common imageproblems. Users have found that the202xi will solve almost any syncrelated problem.

STANDARD SYNC PROCESSINGTo understand why ADSP™ makesa difference, it is necessary tounderstand how an interfacetypically accomplisheshorizontal/vertical shifting and synccombining. Both of these opera-tions are performed in many inter-faces. Unfortunately, these opera-tions change the sync in such a waythat it becomes unacceptable formost digital displays.

Horizontal shift is achieved byshifting the sync signal in relationto the video signal. Figure 1showsan example of a video signal (thered channel), with respect to thehorizontal sync signal. To shift thevideo on the screen, it is necessaryto shift the horizontal sync signal inrelation to the video signal. Thesimplest way to do this is to delaythe horizontal sync signal. Doingthis will allow the image on thescreen to be moved to the left. Anexample of delaying the sync isshown in the lower part of Figure 1.

Delaying the sync signal withrespect to the video signal will

allow shifting of the image to theleft, but not to the right. Shiftingthe image to the right is notpossible since that would requiremoving the sync signal in theopposite direction time-wise. Thiswould require creating the syncpulses before they are generated bythe source. In order to gain theability to shift an image both rightand left horizontally on a screen, itis necessary to delay the sync inrelation to the video signal by oneline of video. Using this method thesync can now be delayed oradvanced in time as needed, and itis now possible to shift the imageon the screen left and right.

Horizontal BlankingPeriod

Video:REDChannel

HorizontalSyncPulse

Active Video

By shifting the Horizontal Sync Pulseto the right(delaying the sync),

the image can be moved to the left.

FIGURE 1


13

Vertical shift (positioning) isaccomplished in a manner similarto horizontal shift, except that thesync is delayed by one vertical fieldinstead of by one line. Other thanthat, the same process of adjustingthe sync in relation to the videosignal is used.

Sync combining is anotheroperation that will alter sync signaltiming. In order to convert RGBHVinto RGBS, it is necessary tocombine the horizontal sync signaland vertical sync signal into onecomposite sync signal. This is doneby using an XOR (exclusive OR)gate. The H&V signals are fed intothe XOR gate and combined into acomposite sync signal. This methodis reliable and is used throughoutthe interfacing industry. However, itdoes change the sync timing byaltering the position of the horizontalsync pulse during the verticalinterval.

DIGITAL DISPLAY DEVICES AND SYNCDigital display devices(LCD/DLP/Plasma) typically needto see a sync signal that has notbeen processed in any way. Anychange in the timing relationshipbetween the video signal and thesync signal, or between the H&Vsync will likely make the syncsignals unacceptable for a digitaldisplay device. This usually results

in tearing, hooking, or bending atthe top of the screen. The originaltiming relationship that existedbetween the video signal and thesync signal must stay intact.

ENTER ADSP™Extron’s exclusive ADSP™ takessync processing to a new level.Through an exclusive digital syncprocessing method, interfaces withADSP™ can shift both vertical andhorizontal sync without creatingany delay. This allows the user tostill use the horizontal and verticalpositioning features even whenusing a digital display device. Aninterface with ADSP™ can alsocombine separate H and V intocomposite sync without altering thesync timing, like an XOR circuit.The resulting signal will be accept-able to most digital display devices.In fact, the resulting signal can beconverted back into separate H&Vand still be acceptable to a digitaldisplay device because the timingwas never altered. Extron productsthat have ADSP™ will also correctsync that has already been alteredeither by horizontal or vertical shiftoperations or by sync combining. Async signal that has already beenaltered by either operation can befed to an Extron interface withADSP™ and the output signal willbe acceptable to a digital displaydevice.

"Since ADSP™

cleans up and

stabilizes the

synchronization

signals, it

prevents many

common image

problems."


14

AP-1500SX BG 6300 DLC POWER 8GV

ExtroNews publishes information about newproducts that are relative to the Extron productline in the New News section. If you would like

a new product to be reviewed for New News,please send a press release, literature, contact

name and a four color slide or photo to:

AADDVVAANNCCEEDD PPEERRIIPPHHEERRAALLSSTTEECCHHNNOOLLOOGGIIEESS,, IINNCC.. ((AAPPTTII))APTi has recently introduced the AP-1500SX, HDLV (High DefinitionLight Valve) Reflective LCD projector.The AP-1500SX weighs 29.3 pounds,offers a true SXGA (1280 x 1024)resolution and a brightness output of1500 ANSI lumens. It offers a hori-zontal scan rate of 15-82 kHz and avertical scan rate of 43-85 Hz. Theprojector has three simultaneous datainputs (13W3, 15 Pin HD,RGBHV/BNC); two simultaneousvideo inputs utilizing S-video (4-pinDIN) and RCA connectors and audioinput on all input signals. Thesuggested list price is $19,995.

Recommended Extron accessories:For computer connection use RGB 202xi,RGB 302/304 or Architectural Seriesinterfaces. For RGB distribution useADA distribution amplifiers, BNCextension cables. Use Lanciaxi linedoubler or Sentosaxi line quadrupler toenhance video signals. For completesystem control, use the System 5cr.

BBAARRCCOO

Barco has recently introduced theBarcoGraphics 6300 DLCDigital LightCanon LCD projector. TheBarcoGraphics 6300 DLC delivers a lightoutput of 2200 ANSI lumens. It offers ahorizontal scan range of 15-81 kHz, avertical scan range of 25-76 Hz and anative resolution of 1024 x 768 withcompatibility up to 1280 x 1024 pixels.BARCO’s unique TCR Plus (True ColorReproduction) provides exceptionallyaccurate colorimetry. The projector offersone composite video (BNC) and one S-video (4 pin DIN) input, one config-urable 5-wire (RGBHV/BNC) input, onestandard VGA (15 Pin HD) input and oneSDI digital input. The unit features threestereo audio inputs, which can beassigned to any input signal by on-screenmenu selection. The suggested list price is$16,495 without lens. A wide range oflens kits are available for the unit rangingin price from $2,000-$5,000.

Recommended Extron accessories:For computer connection use RGB 202xi,RGB 302/304 or Architectural Seriesinterfaces. For RGB distribution useADA distribution amplifiers, BNCextension cables. Use Lanciaxi linedoubler or Sentosaxi line quadrupler toenhance video signals.

DDIIGGIITTAALL PPRROOJJEECCTTIIOONN

Digital Projection has recently introducedthe POWER 8gv, the brightest DLP-based projector available. The POWER8gv has a horizontal scan range of 15-90kHz, a vertical scan range of 24-100 Hz,a native resolution of 1024 x 768 withcompatibility up to 1280 x 1024 pixels. Itoffers 8000 peak (7500 ANSI) lumensbrightness and composite video decodingtechnology by Faroudja Laboratories. Theprojector inputs are: RGBHV/BNC,component video, S-video and compositevideo. The suggested list price is$110,000.

Recommended Extron accessories:For computer connection use RGB 202xi,RGB 302/304 or Architectural Seriesinterfaces. For RGB distribution use ADAdistribution amplifiers, BNC extensioncables. Use Lanciaxi line doubler orSentosaxi line quadrupler to enhancevideo signals.

Pat Charlton, New NewsExtron Electronics1230 South Lewis StreetAnaheim, CA 92805Phone: (714) 491-1500 ext. 6244


15

VPL-X2000UCP-X955W LP 435Z

IINNFFOOCCUUSS

InFocus has recently introduced theLP435z DLP™Personal Projector. TheLP435z weighs 7.4 pounds andmeasures just 9" x 12" x 3.9". It iscompatible with XGA, SVGA, VGA,Macintosh, Full NTSC, NTSC 4.43,PAL and SECAM. It offers 1000 ANSIlumens, true XGA resolution 1024 x 768,a horizontal scan range of 21.24-68.68kHz and a vertical scan range of 50-85Hz. The computer input connections aremade through the InFocusCableWizard™ 3 System(RGBHV/BNC and 15 Pin HD) and the videoinput through a separate S-Video (4 pinDIN), composite video (BNC) or RCAconnector. The suggested list price is$6,999.

Recommended Extron accessories:Recommended Extron accessories: ForVGA use the P/2 DA2 PLUS, VGAswitchers, and VGA plenum cables.For Macintosh use the Mac DA2PLUS and our Mac/VGA adapters. ForRGBHV/BNC systems use the RGB190 and 15HDM-RGBHVF adapter.To get video into the VGA switcheruse the VLD 50. For complete systemcontrol, use the System 5cr.

SSOONNYY

Sony has recently introduced theVPL-X2000U LCD projector. TheVPL-X2000U has a horizontal scanrange of 15-94 kHz, a vertical scanrange of 50-120 Hz and a native reso-lution of 1024 x 768. It is the onlyprojector to incorporate a 4 lampsystem, which provides 2400 ANSIlumens brightness output and thecomfort of redundancy. If one bulb, oreven two bulbs should go out, theprojector will continue to operate.The projector inputs are:RGB/component (RGBHV/BNC),composite video (BNC) and S-video(4 pin DIN). The VPL-X2000U hastwo open input slots for use withoptional Sony IFB input boards andcan be used with optional SU-PJ2000stacking stand for even greater bright-ness output. The suggested list price is$24,990 without a lens. A variety ofoptional lenses are available for usewith the VPL-X2000U.

Recommended Extron accessories:For computer connection use RGB202xi, RGB 302/304 or ArchitecturalSeries interfaces. For RGB distributionuse ADA distribution amplifiers, BNCextension cables. Use Lanciaxi linedoubler or Sentosaxi line quadrupler toenhance video signals.

HHIITTAACCHHII

Hitachi has recently announced theintroduction of its next-generationLCD projector, the CP-X955W. TheCP-X955W offers a brightness outputof 1,100 ANSI lumens, true XGA(1024 x 768) resolution with compati-bility up to 1280 x 1024, a horizontalresolution of 15.7-80 kHz and avertical resolution of 50-85 Hz. Theprojector inputs are: RGB (15 pin HDx2), S-video (4 pin DIN) andcomposite video (RCA x2). The CP-X955W weighs 17.8 pounds andhas a suggested list price of $11,995.

Recommended Extron accessories:For VGA use the P/2 DA2 PLUS,VGA switchers, and VGA plenumcables. For Macintosh use the MacDA2 PLUS and our Mac/VGAadapters. For RGBHV/BNC systemsuse the RGB 190 and 15HDM-RGBHVF adapter. To get video intothe VGA switcher use the VLD 50.For complete system control, use theSystem 5cr.


16

For the past four years, Extron’s website has been aconvenient information source available 24 hours aday, seven days a week. In our continual efforts tomake the site easier to use, we’ve redesigned it bymaking navigational changes, reorganizing cate-gories, adding dynamic navigational menus, andstoring the site’s contents in a database. As IvanPerez, Vice President, Information Technologies,states, “The site redesign exemplifies Extron'scommitment to our customers by providing easyaccess to information regarding our products andservices. This database-centric site is the first in aseries of planned improvements for 1999.”

Changes to the website occurred at the user-end andthe server-end. First, a visitor to Extron’s website willuse a new navigational interface that is moredynamic and intuitive to use. We’ve added drop-down menus to the main menu at the top of eachpage. Point to a category title and a dynamic menuautomatically pulls itself down. All the downloadableitems will be accessible through one centralizeddownload library Web page. This will make down-loading catalog PDF’s or Windows®-based controlsoftware programs more efficient and convenient.

Second, at the server-end of the website, changeswere made to ensure that all information stayscurrent and accurate. Most significantly, the site hasbeen converted to a database-driven architecture.Andy Todd, Extron’s Senior Web Developer, states,“All the website’s content is centralized in one

database, so any changes incontent are instantaneouslyapplied to all relevant articles andproduct pages.” The newdatabase will provide informationmore efficiently and effectively tousers. In addition, the searchengine has been revamped tomake it easier to locate pertinentmaterials. Search engine flexibilityis increased because now searcheshave access to all materials in onecentral location. And users canlimit the search to one section ofthe site, such as “Products” or“Tech Articles”.

Extron is proud to introduce itswebsite’s latest design—noweasier-to-use and more interac-tive—accessible athttp://www.extron.com.

The New Look and Feel of Extron’sDynamic Website

Extron introduces the VSC 200D and VSC 300Dcomputer to video scan converters with digital output.For premium videoconferencing, broadcasting, and display applications, these scan converters offer thehighest level of quality and performance in their class.

The VSC 200D autoscans resolutions up to 1280 x1024, horizontal scan rates up to 81 kHz and verticalscan rates up to 120 Hz for use with high resolutionvideo signals including XGA, SUN, SGI, and highVESA rates. It also features VGA and Mac inputs andcomposite, S-video, component and RGBHV ouputs.An additional 4:2:2 output module is included for con-necting to D-1 decks or digital video editing stations.

The VSC 300D converts computer images up to 1600 x 1280 and offers eight levels of horizontal andten levels of vertical filtering, giving the VSC 300D themost stable, flicker-free image available. To run highresolution computer-video on digital displays such asLCD, DLP, and Plasma, workstations resolutions maybe scaled to as low as 640 x 480. For home theaterapplications, the VSC 300D outputs HDTV 720p.

The VSC 200D/VSC 300D feature:

• Autoscanning up to 1280 x 1024 (VSC 200D model) and up to 1600 x 1280 (VSC 300D model)

• Broadcast quality RS-170A standard output

• Four/eight selectable levels of horizontal (anti-aliasing)filtering

• Five/ten selectable levels of vertical (anti-flicker) filtering

• Horizontal and vertical centering/pan and zoom

• 200% zoom

• Simple Instruction Set (SIS™) for RS-232 control

• NTSC and PAL output compatibility

• 30 user memory locations with autosave and recall; 100 factory presets

• Digital output: CCIR 601, 4:2:2

The VSC 200D has a list price of $4,995. For more informationvisit our website at http://www.extron.com/product/vsc200.stm

The VSC 300D has a list price of $7,745. For more informationvisit our website at http://www.extron.com/product/vsc300.stm

EXTRON ELECTRONICS/RGB SYSTEMS, INC.1230 South Lewis Street, Anaheim, CA 92805800.633.9876 714.491.1500 FAX 714.491.1517U.S.A.

EXTRON ELECTRONICS, EUROPEBeeldschermweg 6C, 3821 AH Amersfoort+31.33.453.4040 FAX +31.33.453.4050The Netherlands

EXTRON ELECTRONICS, ASIA41B Kreta Ayer Road, Singapore 089003+65.226.0015 FAX +65.226.0019Singapore

EXTRON ELECTRONIC INFORMATIONEXTRONWEB™: www.extron.comEXTRONFAX™: 714.491.019224-hour access—worldwide!

800.633.9876

Digital (4:2:2) OutputVideo Scan Converters


18

system (seeFigure 2). Adding the twolines together causes the Chroma tocancel itself thereby providing theLuma information. Why? In theNTSC system, the chroma burstreference and the chroma informationis reversed by 180 degrees on alternatelines. Going back to the early days,this phase reversal effect caused theperceived luminance of the system toremain constant even though the colorsubcarrier is superimposed upon theluma information. [Remember that thecolor system was mandated to provideacceptable performance on mono-chrome receivers.] Conversely,subtracting the delayed line from thecurrent line cancels the luma portionand provides the chroma signal. Takea look at the shape of the typicalsystem responses in Figure 3to seewhy we call it a “comb filter”.Comparing the Y and C frequencycomponents in the correct time rela-tionship creates a filter system wherevery little luma or chroma cross overinto the wrong processing channel.This greatly improves horizontal reso-lution. (Until recent years, combfilters were analog implementationsusing glass delay lines,or SAWs,(surface acoustic waves) or charge-coupled devices (CCDs) to obtain therelatively long delay for an entire hori-zontal line. Today, most designs aredigital utilizing A/D and D/A conver-sion with memory chips providing thedelays needed for digital processing ofthe signal to derive luma and chroma.)

The action described above occurs contin-uously on a line-by-line basis thusproviding a simultaneous flow of Y and Cinformation. But, the “combing” action islimited to the immediate picture fieldbeing received. If the image is static, thecombing is very near perfect. Anobvious, perhaps objectionable artifact isthe transition between different colorsvertically through the picture. Forexample, moving from a red areadownward to a green area creates ayellow line at the horizontal boundarybetween the two colors, since one red linewould be delayed and added to the firstgreen line. Worse yet, when motion isinvolved, the cancellation effect isimperfect and gives rise to various imageartifacts.

Adding a second delay path to create a 2-line comb filter, Figure 4, can helpreduce the problems with color bound-aries. Here, two horizontal lines aredelayed and added back to the incomingvideo information. Considering that atotal of three lines of information areinvolved, the information after the firstdelay will become the “middle” line inthe sequence. The incoming video iscompared at a weighted value of one-fourth, the last delay weighted by one-fourth, and the first delay weighted byone-half. Therefore, at horizontal bound-aries of colors, the transition from onecolor to another is softened. Perhaps thelargest disadvantage to the 2-line combfilter is that vertical resolution suffers dueto the constant weighted averaging of

picture information. For this reason,other forms of adaptive comb filters aremore popular for professional applica-tions, but cost more.

THREE’S COMPANYIf two lines are better than one, then threeshould be better yet, right? Yes,depending. In most cases, more resolu-tion and color decoding improvementmay be obtained. The processing formatis similar to the 2-line comb, but mayutilize additional averaging methodsbetween line samples and typicallyprovides more decisive control. Dependingon implementation, additional verticalresolution may be lost.

All line combs suffer from “chroma meshfailure” when images contain verticalcolor changes. At the color transition, theimage information is changing such thatsome chroma is not cancelled and ispassed through as luma information,causing cross-luminance effects…or, thetypical “hanging dots” at the transitionpoint. Diagonal lines present anotherdifficult situation as luma information ischanging position from line to line.Samples of the luma do not match with

One HorizontalLine (1-H)

Delay

Y CHANNEL

C CHANNEL

Composite

NTSC

+

-

FIGURE 2. SINGLE LINE COMB FILTER

Horizontal frequency multiplesfH

Luma energy

0

Chroma energyinterleaved

3.58 MHzSubcarrier

Horizontal frequency multiplesfH

Y Comb Filter Responce

0

C Comb Filter Responce

3.58 MHzSubcarrier

FIGURE 3. COMB FILTER RESPONSE

Continued from page 5–Comb Filters


19

instructor’s PC applications. “The LCDmonitors being only four inches deepallowed us to maintain a minimum ofstation depth,” says RJC.

Also at the instructor’s station (here and inthe Moots) are Extron RGB 404 and RGB406 architectural computer-video interfaces.The RGB 404 is reserved for guest presen-ters and also provides auxiliary compositeand S-video inputs to the system. The RGB406 is affixed to the instructor’s PC. Unlikethe RGB 324 buffers used in MootBoardrooms, these single computer inter-faces do all signal conversion within thedevice itself and then route the signalthrough an Extron CrossPoint 84HVAmatrix switcher. Computer and other RGBsignals are then converted to NTSC via anExtron scan converter and sent to a matrixswitcher used strictly for NTSC sources.From here, computer signals may be usedin videoconferencing, recording, or bedisplayed on the 50" monitor cubes.

IN CONCLUSION“The promise of what Mandeville Hall isbringing to St. Joseph’s is what gets us themost attention,” says Joseph Lunardi,Director of External Relations at St.Joseph’s. “This is one of the few facilitiesof its kind anywhere in this part of thecountry.” Besides aiding in instruction at St.Joseph’s, the facilities within MandevilleHall have attracted the attention of non-profit groups, other universities, andgovernment agencies that normally wouldnot have access to anything like the tech-nology available there. When asked if hisvision of a “traditional learning experience,enhanced greatly by technology” had beenfulfilled, Rev. Rashford replied pointedly,“By and large, we have succeeded.” SaysRich Coluzzi from RJC: “Our goal was totake an innovative, system-wide designapproach along with the visions of theUniversity to the next level while not losing focus on the goals and needs of thefacility. I believe we have accomplished ourgoals at Mandeville Hall.”

Continued from page 9–St. Joseph’s Install

1-HDelay

Y CHANNEL

C CHANNEL

Composite

NTSC

+

-

1-HDelay

14/

14/

14/

14/

12/

12/

FIGURE 4. 2-LINE COMB FILTER

prior or later samples and an artifact iscreated. The non-cancelled luma passesthrough into the chroma system andbecomes the “rainbow effect” seendancing about on areas where predomi-nant luma detail having oblique anglesoccupies the image.

COMB WHEN YOU CANMost implementations of comb filterstoday are digital. Even when theinternal design is a digital line comb,there is some intelligence usuallyincluded with these filters. Why? Thedigital comb filter must operate withprecise timing in order to provideproper cancellation of luma andchroma. If the luma and chroma timingrelationships are lost, the image qualityis worse than when using anotch/bandpass filter.

So, most digital comb filters regularlymake decisions on when to implementthe comb and when to implement thenotch/bandpass approach. This occursmost predominantly with standardVCRs. The signal timing from a VCRis not capable [without a timebasecorrector] of providing the pixel-to-pixel accuracy required in a digitaldecoder. During VCR playback, adisplay’s digital decoder detects thelarge signal phase errors and automati-

cally switches back to thenotch/bandpass mode of Y/C sepa-ration that was discussed in the lastarticle. Considering that the realiz-able resolution from the typicalVCR is not any better than theperformance of a goodnotch/bandpass design, you will notsee much difference in performance.Certainly, there is some exceptionfor picture quality here with the useof S-video type recording andplayback, but that application is notthe most common for analog VCRs.For extremely stable sources suchas direct broadcast or DVD, thecomb filter will switch intooperation.

ADAPT OR DIE!The next steps in comb filter tech-nology lead to adaptive techniquessuch as 2D and 3D motion adaptivecombing. Image motion is the baneof line-based comb filters.Adaptation allows the system furtherdecision-making capability duringadverse image content changes.Unfortunately, this topic will have tobe the next, and final, episode in thisseries on NTSC decoding basics.Unlike the horizontal dots in a cheapcomb filter, there’s no intention tokeep you hanging.

For past articles, go to http://extron.com/extronews/index.html


Extron School and Extron School On the Road Schedules

1999 ClassesMay 11-12 Extron School On the Road Miami, FLMay 13-14 Extron School On the Road Miami, FLMay 20-21 Extron School, Sales Class Anaheim, CAJune 13-14 Extron School International Orlando, FLJuly 15-16 Extron School Technical Class Anaheim, CAJuly 20-21 Extron School On the Road Seattle, WAJuly 22-23 Extron School On the Road Seattle, WAJuly 26-27 Extron School The Netherlands

•1999•TRADESHOW SCHEDULE

April 19-22 NAB Las Vegas, NVApril 29-May 1 NSCA Nashville, TNMay 17-20 SID San Jose, CAJune 8-12 INFOCOMM Orlando, FLAug 27 MVP Trainex Washington, DCSept 15-17 INFOCOMM Asia SingaporeSept 21-22 CMS Atlanta, GASept 24-26 CEDIA Indianapolis, INOct 6-7 Rocky Mountain Film & Video Denver, COOct 19-22 SATIS Paris, FranceNov 3-5 TELECON Anaheim, CANov 8-10 INFOCOMM Europe Cologne, GermanyNov 29-Dec 2 I/ITSEC Orlando, FL

Extron is pleased to announcethe promotion of Joe da Silva toSenior Product Manager. In hisnew position, Joe will take agreater role in the marketing,promotion and strategic posi-tioning of Extron’s new products.

Joe has been with Extron for thelast eight years, and has been aProduct Manager since July of1996. In this role, he has focusedprimarily on the developmentand marketing of Extron’s matrixswitchers, video processingequipment and digital productlines. Joe has been responsiblefor many of Extron’s newproducts and product redesigns.

Joe holds a Bachelor’s of Sciencedegree in EngineeringTechnology from California StateUniversity, Long Beach, and hascompleted certificates incompetitive manufacturing oper-ations and marketing fromUniversity of California, Irvine.Prior to Extron, Joe wasemployed by IBM.

JOE DA SILVA

Extron’s InternalPromotion

ss 200: required for system upgrades · the ss 200 has a jack for 12 vdc power; a 12 vdc supply can...

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