Hai-Han Lu ()hhlu@ntut.edu.tw

National Taipei University of TechnologyInstitute of Electro-Optical Engineering

OutlineOutlineCATV & HFC systemCATV & HFC system

Measured instrumentMeasured instrument

Technical regulationTechnical regulation

Measured techniqueMeasured techniqueOpticsOptics

ElectricsElectrics

MonitorMonitor systemsystem

ConclusionConclusion

Broadband - CATVCATV means that use lines to transfer programsCATV means that use lines to transfer programs

CATV can compensate for insufficient air channelsCATV can compensate for insufficient air channels

CATV is a kind of local communicationsCATV is a kind of local communications

Fiber brings a lot of benefits in Data Communication Fiber brings a lot of benefits in Data Communication also in CATV systems also in CATV systems

CATV Head End

Program Provider

Satellite

Processing PathProcessing Path

Frequency DistributionFrequency Distribution

0 100 200 500300 400 600 800700 900

Frequency (MHz)

Up-stream Analog broadcast video Digital video

Down-stream

170 180 190 200 210 220

.6 MHzUp-stream 10~40 MHz

Down-stream

Analog 50~550 MHz

Digital 550~750 MHz

Frequency DistributionFrequency Distribution

fv fc fa3.579545 MHZ

4.5 MHZ

6 MHZ

Frequency

Tree ArchitectureTree Architecture

.

. .

.

.

Central office

Splitter

Splitter

Splitter

Metro

Suburban

LAN

Easy to build

Need many amplifiers

CATV Transmit SystemCATV Transmit SystemMTVMTV

LDLD

VCRVCR

SatelliteSatellite HEAD END

Trunk Amplifier

SplitterTap

Bridger Amplifier

Line Extender

Directional Coupler

Power Supply

Tap

Distribution Line

Feeder Line

Drop Line

Home Office OfficeHome

Disadvantages of CATV SystemsDisadvantages of CATV Systems

Using many amplifiersUsing many amplifiers

Reduce signal quality

Not easy to repair

Have EMI distortionHave EMI distortion

Use TreeUse Tree--Branch Structure Branch Structure

Not easy to expandNot easy to expand

Optical Communication DevelopingOptical Communication Developing

LaserLaserFF--P laserP laserDFB laserDFB laser

FiberFiberSingleSingle--modemodeMultiMulti--modemode

Optical AmplifierOptical AmplifierEDFAEDFASOASOARaman amplifierRaman amplifier

WDMWDM

Multi-copper paircable

EDFA

Filter

EDFA ReceiverTransmitter

EDFA ReceiverTransmitterFiber

EDFA EDFA

High PoutMedium NF Low NF

High gain

Direct/ external modulation

Direct/ external modulation

High PoutMedium NF

High PoutHigh gainLow NF

PIN/ APDEasy to repairreliable

PIN/ APD

L1 ~ 20dBLn ~ 30dB

Pin ~ -15dBm

Easy to Upgrade

J. W. Liaw

Repeaterless to remote pumping

Advantages of Fiber Optical CATV SystemsAdvantages of Fiber Optical CATV Systems

Advantage of Fiber CATVAdvantage of Fiber CATV

Improved video signal qualityImproved video signal qualityExpand CATV using bandwidthExpand CATV using bandwidthExtend CATV transmission regionExtend CATV transmission regionIncreased system reliabilityIncreased system reliabilityDecreased EMI effectDecreased EMI effectIncreased compatibilityIncreased compatibility

HFC Systems

AM-VSB Hybrid Digital /Analog

HeadEnd

1 x N coupler

Fiber

1.32m Nd-YAG

1.3m DFB-LD

1.55m DFB-LD

LiNbO3Mod. EDFA

1 x N coupler

1 x N coupler EDFA

node

Coax/ ADSL

1 x N coupler

1 x N coupler

node

node

LiNbO3Mod.

Measured Instrument for CATV

Optical SignalOptical SignalOptical spectrum analyzer (OSA)Optical power meterOptical time domain reflectometer (OTDR)Bit-error-rate Test (BERT)Digital scope

Radio Frequency (RF)Radio Frequency (RF)Spectrum/CATV analyzer (HP-8591C)

OSAOSAMeasured optical spectrum, central wavelength, width, Measured optical spectrum, central wavelength, width, and optical powerand optical powerThe features of the OSAThe features of the OSA

Performance compliant with optical communication devicesPerformance compliant with optical communication devicesWavelength resolution10pm or higherWide dynamic range60dB or moreHigh wavelength accuracy20pmPolarization dependency0.05dB

WDM analysis functionWDM analysis function

OSA SetupOSA SetupInterferometric MethodRotating GratingFixing Grating

Power MeterPower MeterTransmitter power measurements (Transmitter power measurements (dBmdBm and W)and W)FiberFiber--link loss testing (dB)link loss testing (dB)Component insertionComponent insertion--loss testing (dB)loss testing (dB)Fiber identification with 2kHz signalsFiber identification with 2kHz signalsLAN installation and maintenance applicationsLAN installation and maintenance applications

FeaturesFeaturesStandard calibrated wavelengthsStandard calibrated wavelengths850, 1300, 850, 1300, 1310, 1550 nm1310, 1550 nmMeasurement rangeMeasurement range6 to 6 to --60dBm60dBmresolutionresolution0.05dB0.05dB

Principle of OTDRPrinciple of OTDR

Functions of OTDRFunctions of OTDR

Measured fiber lengthMeasured fiber lengthMeasured broken positionMeasured broken positionAverage loss of fiberAverage loss of fiberSplice loss of fiber Splice loss of fiber

BERTBERTBuiltBuilt--in precision synthesized clock generatorin precision synthesized clock generator10 MHz thru 3.6 GHz10 MHz thru 3.6 GHzVariety of test patternsVariety of test patterns

Pseudorandom (PRBS) pattern 2Pseudorandom (PRBS) pattern 2nn--11(n(n7, 9, 10, 11, 15, 23 or 31)7, 9, 10, 11, 15, 23 or 31)

Bit error measurementBit error measurementError rateError rateError countError count

Digital ScopeDigital Scope

Making eye diagram measurementMaking eye diagram measurementMeasuring extinction ratioMeasuring extinction ratioMeasuring jitterMeasuring jitterMeasuring QMeasuring Q--factorfactorMeasuring rise timeMeasuring rise timeMeasuring fall timeMeasuring fall time

HPHP--8591C8591CMeasured RF spectrum frequencyMeasured RF spectrum frequencyMeasured CNR, CSO, CTB, and XMODMeasured CNR, CSO, CTB, and XMODFrequencyFrequency

RangeRange9KHz~1.8GHz9KHz~1.8GHzFrequency accuracyFrequency accuracy5x105x1077 of central of central frequency frequency 700Hz700HzSpan accuracySpan accuracy 3%3%RBWRBW300Hz~5MHz300Hz~5MHz

Measured rangeMeasured range--139 ~ +20dBm139 ~ +20dBmReference level rangeReference level range--70 ~ +20dBm70 ~ +20dBmAttenuation rangeAttenuation range0~50dB0~50dB

Optical Transmitter

DFB/FP LD

Modulation

DFB/FP LD DFB/FP LD (light source)(light source)DFB LDDFB LD

Single mode (@1550nm)Single mode (@1550nm)

Low chirpLow chirpLow RIN (< Low RIN (< --155dB/Hz)155dB/Hz)

FP LDFP LDMultimode (@1550nm)Multimode (@1550nm)

High chirpHigh chirpHigh High RIN (< RIN (< --120dB/Hz)120dB/Hz)

Optical Light SourceOptical Light Source

ModulationModulationDirectly modulation

Source : DFB LDSource : DFB LDSimple architecture, High reliability, Low cost, Low output poweSimple architecture, High reliability, Low cost, Low output powerrSuper trunk (one point to one point)Super trunk (one point to one point)Short or middle distancesShort or middle distances

External modulationSource : DFB LD + External ModulatorSource : DFB LD + External ModulatorControl circuit complexity, Expensive, High output powerControl circuit complexity, Expensive, High output powerFiber backbone (one point to multiFiber backbone (one point to multi--point)point)Long haulLong haul

Modulation SetupModulation Setup

Driver

Laser

Opticalpulses

OpticalModulator

Driver

Laser

Voltage

Voltage

Direct Modulation External Modulation

Opticalpulses

Transmission

FiberEDFA

Transmission MediaTransmission Media

100 MHz200 dB / full pathSatellite

100 GHz0.4 dB / km (1310 nm)0.24 dB / km (1550 nm)

Fiber

750 MHz5 dB / 100 mCoaxial cable

3.3 kHz1 dB / kmTwisted pair

BandwidthTransmission loss

FiberFiberFiber structureFiber structure

CoreCoreCladdingCladdingJacketJacket

TypeTypeSingleSingle--modemodeMultiMulti--modemodePlastic fiberPlastic fiber

Reflection indexReflection indexStepStep--IndexIndexGradedGraded--IndexIndex

Coaxial electric cord v.s. FiberCoaxial electric cord v.s. Fiberaluminumaluminum

Central conductorCentral conductor

Magnetic linesMagnetic lines

Electric linesElectric lines

PlasticPlastic

CoreCore

CladdingCladding

CladdingCladding

CoreCore

RF Signal

60 Hz AC60 Hz AC

Coaxial

Fiber

Fiber ParametersFiber Parameters

Fiber diameterFiber diameterNumerical apertureNumerical apertureCutCut--Off wavelengthOff wavelengthAttenuationAttenuationAbsorptionAbsorptionDispersion coefficientDispersion coefficient

Fiber AttenuationFiber Attenuation

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Wavelength (m)0.1

1.0

10

Atte

nuat

ion

(dB/

km)

Low water peak fiber

Standard water peak fiber

1625-1675 U-band1565-1625 L-band

1530-1565 C-band1460-1530 S-band1360-1460 E-band

1260-1360 O-band

O = OriginalE = ExtendedS = ShortC = ConventionalL = LongU = Ultra-long

EDFAEDFAAmplified laser powerAmplified laser powerASEASEBasic ComponentsBasic Components

Pump laserPump laserGain fiber (ErGain fiber (Er3+3+))IsolatorIsolatorWDM couplerWDM couplerPhoto diodePhoto diode

EDFA EDFA -- ASEASE

Without signal inputWithout signal input With signal inputWith signal input

EDFA Pumping Structure EDFA Pumping Structure

Forward pumpingForward pumpingBackward pumpingBackward pumpingDual pumpingDual pumping

Signal

980/1480nm LD

WDM

EDF

Forward pumping

EDF 980/1480nm

LD

Signal WDM

Backward pumping

980/1480nm LD

EDF

WDMSignal

980/1480nm LD

Dual pumping

Characteristics of EDFACharacteristics of EDFA

High gainHigh gain

Low noise figureLow noise figure

BroadbandBroadband

Gain flatnessGain flatness

High reliabilityHigh reliability

Technical RegulationSystem formSystem formModulated formModulated formAMAM--VSBVSBFMFMMultiplexer formMultiplexer formFDMFDMWDMWDMDWDMDWDM

Measured Technique

Quality DemandQuality Demand

535353534343Subscriber (dB)Subscriber (dB)

60/6560/6560/6260/625050Fiber node (dB)Fiber node (dB)

CTBCTBCSOCSOCNRCNR

Measurement in CATV SystemMeasurement in CATV System

A B C

1. Signal Generator

2. Pattern Generator

3. RF Sweeper

4. BaseBand Sweeper

1. Modulator

2. Signal Processor

3. Distribution NetWork

1. 2. 3. 4. 5. ()6. 7. 8. 9.

10. 11. 12.

Optical Test EquipmentOptical Test EquipmentOTDROTDRFiber Fiber splicersplicerOSAOSAPower meterPower meterOptical fiber probeOptical fiber probe

Fiber leakage measuredFiber leakage measuredFiber detectorFiber detectorOptical fiber phoneOptical fiber phone

Immediate communicationImmediate communicationVOA VOA

OSAOSACentral wavelength

Peak power3dB linewidth

Power MeterPower Meter

EDFAEDFATransmitter

Fiber

Receiver

PIN/ APD

Fiber

OTDROTDR

Digital Scope Digital Scope Eye patternEye pattern

2.5 Gbps

Fig. a Launch power-1dBm Fig. b Launch power-18dBm

EDFAEDFATransmitter

Fiber

Receiver

PIN/ APD

Fiber

DigitalScope

The Parameter of RF Signal in CATVThe Parameter of RF Signal in CATV

Video/Audio Carrier Level/FrequencyVideo/Audio Carrier Level/FrequencyIMIMCNR/CSO/CTBCNR/CSO/CTBXMODXMODHUM/LFDHUM/LFDRadiation LeakageRadiation LeakageSystem Frequency ResponseSystem Frequency ResponseInIn--Channel Frequency ResponseChannel Frequency Response

Carrier to Noise Ratio (CNR)Carrier to Noise Ratio (CNR)

fc fc + 4.5 MHz

CNR43 dB Noise Level

Audio carrier frequency

Video carrier frequency

Composite Second Order (CSO)Composite Second Order (CSO)

fc fc + 4.5 MHz

CSO53 dB

fc + 1.25 MHzfc - 1.25 MHz

fc+

0.75

MH

z

fc-0

.75

MH

z

Audio carrier frequency

Video carrier frequency

Composite Triple Beat (CTB)Composite Triple Beat (CTB)

fc fc + 4.5 MHz

CTB 53 dB

Audio carrier frequency

Video carrier frequency

Cross Modulation Ratio (XMOD)Cross Modulation Ratio (XMOD)

fc fc + 4.5 MHzfc + 15.734 KHz

XMOD 46 dB

Audio carrier frequency

Video carrier frequency

The Parameters in the User EndThe Parameters in the User End

Turn off modulation Turn off modulation signalsignal

Turn off modulation Turn off modulation signalsignal

Turn off carrierTurn off carrier

Turn off modulation Turn off modulation signalsignal

RemarkRemark

6 %6 %

1 dB1 dB

40 dB40 dB

46 dB46 dB

53 dB53 dB

43 dB43 dB

Low than video Low than video level 13 ~ 17 dBlevel 13 ~ 17 dB

0 ~ 14 0 ~ 14 dBmVdBmV

StandardStandard

Echo ratingEcho rating

System frequencySystem frequencyresponseresponse

HUM modulation ratioHUM modulation ratio

XMODXMOD

CTBCTB

CNRCNR

Audio carrier levelAudio carrier level

Video carrier levelVideo carrier level

Carrier to Hum RatioCarrier to Hum Ratio

40 dB40 dB

Carrier to Hum RatioCarrier to Hum Ratio

Echo RatingEcho Rating

Head End

.User End

Amplifier Splitter Amplifier

6 dB6 dB

Echo RatingEcho Rating

Cross Modulation Ratio (XMOD)Cross Modulation Ratio (XMOD)

46 dB46 dB

Measurement of CATV SystemMeasurement of CATV System

Modulator of the Head EndModulator of the Head EndDifferential GainDifferential GainDifferential PhaseDifferential PhaseChrominance to Luminance Delay InequalityChrominance to Luminance Delay Inequality

User EndUser EndEcho RatingEcho RatingPicture & SoundPicture & Sound

Monitor system

System Setup System Setup CH02CH03

CH77CH78

OpticalTransmitter EDFA

SMF

OpticalReceiver

OpticalReceiver

TriggerCircuit

TriggerCircuit

MobilPhone

MobilPhone

C

A

B

OTDR

OpticalTransmitter EDFA

CH02CH03

CH77CH78

HP-8591COpticalReceiver

1310/1650 nm

1550 nm

1550 nm

WDMMUX

1310/1650 nm

SMF

WDMDEMUX

CH02CH03

CH78

MUX/DEMUX

OpticalTransmitter

OpticalReceiver

SMF

OpticalReceiver

OpticalTransmitter

TransponderTransponderReceiver

OTDR

Cheetah

ConclusionCritical system parametersCritical system parameters

Electrics Carrier / Audio levelCarrier / Audio levelCNRCNRCSOCSOCTBCTBXMODXMODIsolationIsolationEcho RatingEcho Rating

Optics LossLossGainGainChromatic DispersionChromatic DispersionWavelengthWavelength

Thanks for your attention!Thanks for your attention!