June 2004 slide 1

Part 2 Calibration

Kjell Bergh

June 2004 slide 2

Content

External vs. in-house calibrationCalibration vs. validation vs. verificationPassive devices

Cables, attenuators, directive couplers, LISN etcActive devices

Preamplifiers, Power amplifiers, Pulse limitersComplex instruments

Receivers, ESD simulators, EFT/B generators, Surge generatorsSystems

Absorbing clamp, Van Veen loop, RF immunity systems, Emission systems

June 2004 slide 3

External vs. in-house calibration

ExternalPreferably accredited calibration laboratoriesManufacturer calibration of specific equipmentOther calibration labs, as long as they maintain traceability

In-houseDepends on own organizationSimple passive devicesRF immunity set-up calibrationNSAChamber field homogeneity

June 2004 slide 4

Calibration vs. validation vs. verification

Priorities to considerEnsure “true” value in measurementAt “all” timesEnsure traceabilityMaintain confidence in labCompetence of personnel

Sequence of eventsCalibration at long intervals (1-3 Yrs)Validation at short intervals (monthly)Verification before each test

June 2004 slide 5

Definitions

CalibrationPeriodic assessment of a piece of equipment or system against a number of defined parameters. Usually performed by an external calibration laboratory, the measurements are traceable to SI standards.

ValidationAn assesment of a piece of test equipment or system against the requirements of the test standard.

An initial validation is performed at the end of test development Regular validations are performed to demonstrate ongoing compliance to the test standard

VerificationA quick and simple measurement or test to ensure that a piece ofequipment or system is functioning correctly

June 2004 slide 6

Calibration

Applied to single instruments, one at a time

Define critical instrumentation parametersCertificate of deviations from nominal valuesCertificate with uncertainty valuesTraceable to SI standards via secondary standardsAccredited

June 2004 slide 7

Validation

Tertiary standard (traceable)Most critical parametersTrend recordApproximation to exact valuesComparison to “fresh” calibrationMay be system oriented

June 2004 slide 8

Trend analysis

Parameter

Time

June 2004 slide 9

Verification

Verify proper functionSingle parameterEasy to testFailure indicates major problemMaximum coverage of instruments

June 2004 slide 10

External calibration

Define important parameters to be calibratedAccreditation scope of cal.lab.If not, may we still rely on the unaccredited calibration?”Pass/fail” verdict or numeric deviations from nominalCombine deviations and calibration uncertainty into equipment uncertaintyTransportationHandling timeRepair and/or adjustments

June 2004 slide 11

Calibration uncertainty

Assume:a) Max. deviation from nominal reading, rectangular distribution

k=√3: δXb) Cal. uncertainty, normal distribution

k=2: Ucal

Then measurement uncertainty:

22 )3

()2

( XUu calreading

δ+=

June 2004 slide 12

Hierarchy of calibration standards

A calibration standard is a unit that specifies a physical parameter

International standardNational standardPrimary standardSecondary standardTertiary standardEtc.

June 2004 slide 13

In-House calibration

Passive devicesCablesAttenuatorsDirectional couplersTransducers like LISN, CDN, ISN, current clamps, antennas

Reference standards (tertiary standards traceable by external accredited calibration):

Receiver with tracking generator

Directional couplerReceiver + generatorNetwork analyzer calibration kitPower meterField probe

Gen Rec.DUC

Reflection measurementRec.

June 2004 slide 14

2bPassive devices

May in many cases be calibrated in-house

June 2004 slide 15

Critical parametersPassive devices

Cables and attenuatorsInsertion lossImpedance all ports (If NA is used)Stability to mechanical stressMatch both ends

Directional couplersInsertion loss all combinations of two portsImpedance all ports (If NA is used)Mechanical stabilityMatch all ports (Through ports most important)

Network analyzer orReceiver with

tracking generator

June 2004 slide 16

Critical parametersPassive devices

LISN (Calibrated externally)EuT port impedance, 9 kHz to 30 MHz.EuT port to RF port insertion loss (may be validated in-house)Line to neutral isolation RF port impedanceAE port isolationAvailability of cal. jig?

LISNEuT port

AE port

RF port

June 2004 slide 17

Critical parametersPassive devices

CDN (Validated only)EuT port to RF port insertion lossAE port to RF port isolationRF port impedance

CDN

RF port

EuT port AE port

June 2004 slide 18

Critical parametersPassive devices

Current clamp (monitor clamp) (External calibration)Conversion factor (Frequency response) Insertion impedance on line under testRF port impedance match

EMF

Iline

June 2004 slide 19

Critical parametersPassive devices

ISN (for telecom ports) (External calibration)

Insertion lossLCLEuT port impedance (common mode to ground)AE port to RF port isolation (alternatively AE to EuT port)RF port impedancePolarity reversal?

ISN

RF port

EuT port AE port

June 2004 slide 20

Critical parametersPassive devices

Antennas (used in emission tests) (External calibration)

AF at sufficiently dense frequency stepsImpedance matchCross-polarization (if applicable)Balance (if applicable)Polar diagram, E- and H-plane, at least to 45° fromboresightCalibration at another OATS than where it is to be used

June 2004 slide 21

Critical parametersPassive devices

High-voltage probe (External calibration)Conversion factorRF port impedance match

1500Ω

June 2004 slide 22

2cSimple active instruments

June 2004 slide 23

Critical parametersActive devices

Pulse limiter (for conducted test) (External calibration)

Insertion lossPulse limiting capability (Verification)Impedance match in- and out-port

10 dB attenuation

June 2004 slide 24

Critical parametersActive devices

Preamplifiers (used in emission tests) (may be calibrated in-house using tertiary standards)

Gain over frequency bandImpedance match, in- and out-port

PreamplifierGain

MatchFreq. span

June 2004 slide 25

Critical parametersActive devices

Power amplifier (Validation)Gain accross bandSmallest max output power levelHarmonic content at 3 dB back-off from max levelImpedance match in- and out-portPower stability with temperatureOverload behaviour

Pout

Psat-3 dB

-8 dB

Pin

June 2004 slide 26

Critical parametersActive devices

Power meter (External calibration)Reading acccuracy with sinewave in (calibrated)Sensitivity stability (time, temperature)Input impedance matchIn-house validation

Meter response to 80% AM rel CW, same generator settingassuming power amplifier in linear mode.

PAM

PCW

PIN,CW

June 2004 slide 27

2dComplex instruments

June 2004 slide 28

Critical parametersComplex instruments

Receivers (for radiated test) (External calibration)Sine-wave response at low levels (+0 to +30 dB relative noise floor)Pulse amplitude response, PK, QP and AV detectorsPRF response for QP detectorInput impedance match with:

Preamplifier on, no input attenuationPreamplifier off, no input attenuationPreamplifier off, 10 dB input attenuation

Noise floor under conditions aboveIF bandwidths as applicableFrequency stability (e.g. that it is OK)

June 2004 slide 29

Receivers

Sinewave response

1 10 100 1000 Hz

QP response to PRF

6 dB bandwidth

Freq.step

N0

Signal

June 2004 slide 30

Critical parametersComplex instruments

Receivers (for conducted test) (External calibration)Sine-wave response at low levels (+50 to +80 dB relative noise floor)Pulse amplitude response, PK, QP and AV detectorsPRF response for QP detectorInput impedance match with:

Preamplifier off, no input attenuationPreamplifier off, 10 to 50 dB input attenuation

Noise floor under conditions aboveIF bandwidths as applicableFrequency stability (e.g. that it is OK)

June 2004 slide 31

Critical parametersComplex instruments

Signal generator (Validation)Output sinewave levels resettability (validation)Modulation index at 80% (calibrated)Effect on RMS power level when modulation is switched ONSinewave purityOutput impedance matchFrequency stability (e.g. that it is OK)Software control stability

June 2004 slide 32

Critical parametersComplex instruments

ESD generator (gun) (External calibration)

Current into 2 ΩAt peakAt 30 nsAt 60 ns

Risetime into 2 ΩLevels:

+ 1, 2, 4, 8 kV- 1, 2, 4, 8 kV

June 2004 slide 33

Critical parametersComplex instruments

EFT/Burst generator (External calibration)

Pulse peak, rise time and 50% timePulse PRF 85 kHz, 2,5 kHz)Burst duration Burst intervalTest durationSettings:

Line - LineLines - Ground+/- polarity

June 2004 slide 34

Critical parametersComplex instruments

Surge generator (Combination wave) (External calibration)

2 Ω source, 12 Ω source, 42 Ω sourceLine – LineLines – Earth1, 2, 4 kVPulse risetime and 50% time, open and short-circuitPulse synchronization with mains phase, 0°, 45°,90°, etc.

June 2004 slide 35

2eSystems

In most cases, the system is validated in-house, but components has external calibration

June 2004 slide 36

Emission

June 2004 slide 37

SystemsCalibration colour semantics

External calibration

In-house calibration

Compensated in set-up

No calibration

EuTPartial calibration

June 2004 slide 38

Critical parametersSystems

Radiated emissionComponents

AntennaAntenna mast w/controlsCables(Preamplifier)ReceiverTurntableSite (OATS or semianechoic room) with ground planeRef. source

June 2004 slide 39

In-House calibrationNSA calibration

Preferably other antennas than normal test antennaBoth antennas calibrated recently (tertiary standard)Receiver/tracking generator recently calibrated (tertiary standard)Appropriate softwareCalibrated cables (fourth-level standard)

Gen. Rec.

June 2004 slide 40

SystemsRadiated emission

EuT

Rec

PreampEN 55022 Sec. 6

Ant

June 2004 slide 41

Critical parametersSystems

Emitted powerComponents

Absorbing clamp (external calibration)Clamp rangePower cableRF cableReceiver (external calibration)(Shielded chamber)Clamp pulling deviceCalibration and verification jigs/targets etc. (external calibration)Supply filters and added absorbers

June 2004 slide 42

SystemsDisturbance power

EuT Clamp

Rec.

EN 55014-1sec. 4.1.2

June 2004 slide 43

Critical parametersSystems

Absorbing clamp (for emitted power) (External calibration)

Conversion factor (Frequency response)Calibration certificateIn-house with small target (ref. measurement on OATS)In-house with jig

RF port impedance matchAE port isolation

June 2004 slide 44

Absorbing clamp calibration

Receiver/generator

Reference plane 2x2 m External calibration

June 2004 slide 45

Absorbing clamp validationIn-House calibration (may also be externalfor comparison)

Receiver/generator

10 dB

Target

June 2004 slide 46

Validation jig

In-House validation at intervals

Receiver/generator

June 2004 slide 47

Critical parametersSystems

Mains conducted emissionComponents

LISNGround planeEuT table / palletReceiverPulse limiterCables

June 2004 slide 48

SystemsConducted emission

EuT

2.LISN

40 cm

Rec

(L)ISN

80 cm

EN 55022 sec. 5

June 2004 slide 49

Critical parametersSystems

Discontinuous disturbanceComponents

LISNGround planeEuT table / palletClick AnalyzerPulse limiterCables

June 2004 slide 50

SystemsClick-noise disturbance

EuT

40 cm

LISN

80 cm

Click-noise

analyzer

EN 55014-1 sec. 4.2

June 2004 slide 51

Critical parametersSystems

Telecom port emissionComponents

ISNCurrent probe, as applicableVoltage probe, as applicableFerrite attenuator, as applicableLISN for power supplyGround planeEuT table / palletReceiverCables

June 2004 slide 52

Telecom port emission

EuT

2.LISN

40 cm

Rec

ISN

80 cm

EN 55022 sec. 9

June 2004 slide 53

Non-invasive measurements

EuT CP Fe-absorber AE

150Ω

Receiverdual

Current probe

EuT CP Fe-absorber AECVP

Voltage probe

Alt. 1

Alt. 2

June 2004 slide 54

Critical parametersSystems

Luminarie insertion lossComponents

LISN, 150 ΩBalunDouble 75 Ω coaxReceiver with tracking generatorDummy tubes, for applicable luminarieCables

June 2004 slide 55

SystemsLuminary insertion loss

EN 55015 sec. 4.2

Luminary

RX/TXcombo

LISNBalun

Pair of 75Ω coax

June 2004 slide 56

Critical parametersSystems

Luminary H-field emissionComponents

Large loop antenna (Van Veen) – Radiated H-fieldReceiverCablesLoop switch controlCalibration probe (inspection for integrity)

June 2004 slide 57

SystemsRadiated H-field emission

Receiver

EN 55015 sec. 4.4

In-house calibration toavoid transportationand include ambient

June 2004 slide 58

Critical parametersSystems

Van Veen loop

June 2004 slide 59

Critical parametersSystems

Harmonics and flicker analyzer (Internal calibration with calibrator. Calibrator calibrated externally)

Power sourceContinous current capability and purityInrush current capabilitySource impedanceVoltage and frequency setting accuracy

AnalyzerCurrent reading 0 – 2000 HzLeast significant reading (mA), each harmonicDmax, Dc, Pst and Plt evaluationSoftware operation, Fluctuating vs. steady harmonicsComparison with limits

June 2004 slide 60

SystemsHarmonics and flicker

EN 61000-3-2EN 61000-3-3

EuT

Powersupply

Analyzer

Impedancenetwork

Harmonics/Flicker

Calibrator

June 2004 slide 61

Flicker characteristics

ZREF = 0,4 + j0,25 ΩRA = 0,25 Ω, XA = j0,15 ΩRN = 0,15 Ω, XN = j0,1 Ω

June 2004 slide 62

Immunity

June 2004 slide 63

SystemsESD immunity test

ESD EuT High-speedoscill.

0,5 mm

HCP

Pellegrinitarget

EN 61000-4-2VCP

June 2004 slide 64

Critical parametersSystems

Radiated RF immunityComponents

GeneratorPower amplifierCablesDirectional couplers(Switches)Antenna(s)Anechoic chamberField probe(s) w/monitorPower meter(s)

Set-up calibration

June 2004 slide 65

In-House calibration

Field homogeneity calibrationCalibrated field probe (tertiary standard)Defined positioning jig for probeDefined antenna positionIf added absorbers, defined positionAppropriate software for job

June 2004 slide 66

SystemsRadiated RF immunity

EN 61000-4-3

EuT

Ant

Gen PA

Pwrm.

Field probemonitor

June 2004 slide 67

SystemsEFT/Burst immunity

EN 61000-4-4

EuT

EFT/Bgenerator

EuT

Cap. clamp

June 2004 slide 68

SystemsSurge immunity

EN 61000-4-5

EuT

Surgegenerator

June 2004 slide 69

Critical parametersSystems

Conducted RF immunityComponents

GeneratorPower amplifierAttenuatorCablesCDNPower meterCalibration jigGround planeCurrent monitor probeMonitor receiver/power meter

Set-up calibration

June 2004 slide 70

In-House calibration

Set-up calibration (immunity) traceabilityCalibrated power meter(s) (tertiary standard)Calibrated field probe (tertiary standard)Directional coupler with sufficient directivityValidated attenuators and cablesVerified CDNsGenerator with calibrated AM(tertiary standard)Table of expected levels

CDN

GEN PA Pwrm.

Set-up calibration

6 dB

June 2004 slide 71

SystemsConducted RF immunity

EN 61000-4-6

CDN

EuT

CDN

GEN PA Pwrm.

Set-up calibration

6 dB

Rec.

6 dB

Testing

10 cm

June 2004 slide 72

Critical parametersSystems

EM clampConversion factorAE port isolationRF port impedance match

Part of set-up calibration, in-house

Receiver/generator

June 2004 slide 73

SystemsPower freq. H-field immunity

EN 61000-4-8

EuT

Power freqCurrentsource

DVM H-fieldmeter

June 2004 slide 74

Critical parametersSystems

Power frequency H-fieldLoop designCurrent generatorCurrent monitorField homogeneity

May be validated in-house

Helmholtz coilSingle loop coil

June 2004 slide 75

SystemsVoltage dips and interruption

EN 61000-4-11

EuT

Simulator