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El entrenamiento 「Radiodifusión digital terrestre」

～Varias mediciones de radiodifusión digital terrestre～

24 d f b d 201024 de febrero de 2010NHK Engineering Administration Department

Ritsuko Okabe1

Ritsuko Okabe

Factor de deterioración y síntoma de la obstrucciónsobre la Calidad de Señal

Cause of Degradationsymptom

Analog Digitalg Analog（NTSC-AM)

Digital(OFDM)

Weak signal strengthSnowy pictureSnowy picture

Picture break up

CN Ratio degradation

Multipath echo Ghosting por freezing

No receptionAdjacent channel interference

Patterns on thescreenCW, booster oscillation screen

IM,CTB

Electrical interference Dots, flashes

■In digital broadcasting …◆ Symptom is the same, regardless of interference type

2

y p , g yp◆Rapid image degradation below threshold（Cliff Effect）

Measurement of Digital Terrestrial TV

■RF Measurement◆ Measurement by spectrum analyzer◆ Measurement by spectrum analyzer◆ Channel power, electric field strength, CNR, signal waveform, etc. g

■Demodulated Signal Measurement◆ Measurement by ISDB-T analyzer◆ Measurement by ISDB-T analyzer

◆ BER, MER, constellation, multipath echo,per-carrier BER per-carrier MERper carrier BER, per carrier MER, BER vs CNR, equivalent noise degradation,noise mergin etc.

■ＴＳ Analysis◆ P t l t b TS l

3

4

◆ Protocol measurement by TS analyzer

Measurement of Digital Terrestrial TV

■Signal strengthChannel power 〔dBmW〕

■RF signal qualityCNR（C i N i R i ）CNR（Carrier to Noise Ratio）

■Demodulated signal qualityBER（Bit Error Ratio）BER（Bit Error Ratio）MER（Modulation Error Ratio）

4

5

PrácticaPráctica

5

（Referencia）Un diagrama del SistemaMPEG RECORDER & PlayerSony Tectronix MTX100

Noise Gen

FADING SIMULATEREIDEN 4401A

OFDM MOD

MIX OFDM MODULATOREIDEN 3501C

EIDEN 4401A

SG

DIST

On-AirSG

Digital TV Signal AnalyzerADVANTEST R3466

OFDMDE-MOD

BER ADVANTESTR2312

（TS）

6MPEG DECORDER TV

Analizador de Señal Digital TV

Software menu bar

Keys on the Panel(Hard Key)

Software menu bar

7

Base de Operación

Select standardCONFIG

F tti

ISDB-T, ISDB-S,CATV 64QAM, CS QPSK,NTSC, Spectrum Analyzer

Frequency settingVHF, UHF, CATV, BS,JCSAT, SUPERBIRD110°CS

FREQ

Function setting110 CS

POWER, FIELD STRENGTH,

FUNC

BER, CNR, MULTI PATH, MER,BER vs CNR etc.

(Parameter setting)10 Key Unit+ (Parameter setting)

S

y

8Start

Preparación de la MediciónPreparación de la Medición

9

Preparación de la Medición

Initialization

Calibration

MEAS. SETUP setting

◆ISDB-T mode settingg

◆MEAS Mode setting

ATT iATT setting

Pre Amp setting

10

Inicialización

MENU

Special

Preset All Initialize all parameters[Default mode][Default mode]ISDB-T Channel PowerATT=10dB, Pre-amp Off

11

Menu Overview

CONFIG FREQ FUNC

12

MEAS. SETUP

ISDB-T mode setting (Default Value:3)

FUNC

g ( )

Guard Interval setting (Default Value:1/8)Other parameters are set automatically from TMCC

GI ＤＡＴＡ

Measuring

10%

30%

50%

70%

FFT Window

FFT Window

FFT Window

FFT WindowMeasuringMode setting FFT Window70%

90%

13

Measurement Modes

FeaturesUsageEnvironment

ISDB-Tmeasurement

dHigh MER measurement (MER>50dB)Ranging is done only at the start; Auto

Single channel output for transmitter / repeater (signal

TransmitterEnvironmentmode

Range processing is not donequality is high and stable).

Auto Range processing is done duringMulti-channel transmissionNormal Auto Range processing is done during measurement to deal with level fluctuations

Multi-channel transmission with little effect of multipath echo and other interference.

Normal

Post-Viterbi BER 2E-4(CR 7/8,64QAM) can be measured under following

i t

Multi-channel transmission under effect of multipath

h d th i t f

Fieldemvironment.

-low electric field (40dBµV)-multipath (D/U 0dB)

Auto Range processing is done during

echo and other interference which prevent measurement in Normal mode

g p g gmeasurement

Checking Noise Floor

Check the noise floor with and without signal input

ATT set to optimum value

LEVEL

OffIncorrect Result

with and without signal input LEVEL

Min ATTOn Set to OffOff

Instrument noise floor

Signal noise floorAuto Level

On Set to Off

Signal noise floor

ATT set to low value, P A t d O

ATT set automatically by the total input power measurement so there is no mixer distortion

Pre Amp turned On

Correct ResultPreamp set to On

PreampOnPreamp

OffAuto Level operation is p required after settingPre Amp On or Off

Instrument noise floor

Signal noise floor

Medición de "Fuerza de Señal"

Medición de la Potencia de CanalesMedición de la Potencia de Canales

16

Medición de la Potencia de Canales

■Channel Power Mesurement◆Total power measurement in the band◆Total power measurement in the band◆Able to measure accurate power of the signal which has in-band amplitude dispersion by multipath echohas in band amplitude dispersion by multipath echo

Parameter of Spectrum AnalyzerParameter

Band Width 5.6MHzResolution Band Width 30kHzVideo Band Width 300kHzVideo Band Width 300kHzDetection Mode SampleAveraging 30times

17

［E t d 1］

Medición de la Potencia de Canales (13Seg)［Entrenando-1］Measurement of 13 Segment Channel Power by Spectrum Analyzer ModeSpectrum Analyzer Mode① [CONFIG]→ Spectrum Analyzer② [Center]→557 142856MHz② [Center]→557.142856MHz

(UHF27ch+0.142856MHz offset)③ [Span]→10MHz③ [Span]→10MHz④ [BW]→RBW→Man→30kHz, VBW→Man→300kHz⑤ [SWEEP]→Man→100ms⑤ [SWEEP]→Man→100ms⑥ LEVEL→ to Screen Center⑦ [FUNC] Cha el Po e Wi do =o⑦ [FUNC]→Channel Power→Window=on⑧ Window Width→5.6MHz⑨ U d S C dB (RMS)

18

⑨ Under Screen C= dBm(RMS) (Unit change ：LEVEL→Units→dBu,dBm)

Medición de la Potencia de Canales (13Seg)

19


■Channel Power measurement■Channel Power measurement・Spectrum Analyzer mode・FUNC Channel Power Window Width=429kHz・FUNC→Channel Power→Window Width=429kHz

■Equivalent from 13segment Channel Power value・characteristics in 5.6MHz band → flat・1seg Power=13seg Power – 11.14dB (=10log(1/13))

20


［Entrenando-1］Measurement of 1Segment Channel Power by Spectrum Analyzer Mode

① [CONFIG]→Spectrum Analyzer① [CONFIG]→Spectrum Analyzer② [Center]→557.142856MHz

(UHF27ch+0 142856MHz offset)(UHF27ch+0.142856MHz offset)③ [Span]→1MHz④ [BW]→RBW→Man→30kHz VBW→Man→300kHz④ [BW]→RBW→Man→30kHz,VBW→Man→300kHz⑤ [SWEEP]→Man→100ms⑥ [FUNC]→Channel Power → Window=on⑥ [FUNC]→Channel Power → Window=on⑦ Window Width→429kHz

21⑧ Under Screen C= dBm(RMS)


22

Intensidad del campo eléctricoIntensidad del campo eléctrico

23

Indicacion de la Intensidad del campo eléctrico

■InformationChannel, Center freq.St d d Ch PStandard, Ch Power■Result

Bar GraphBar Graphread “average” value

24

Medida de "Calidad de signo"

Medición la Tasa de CNMedición la Tasa de CN

25

Definición de CNR

■The Ratio of carrier Power to the Noise power■The Ratio of carrier Power to the Noise powerin OFDM band width(5.57MHz)

Average Carrier level：Crms[V]Average Noise level ：Nrms [V]Average Noise level ：Nrms [V]

CN = C N [dB]CN = Crms－Nrms [dB]【dB(V)=20log10 (V)】

26

Medición la Tasa de CN

［Entrenando-2］CNR mesurement

① CONFIG→ISDB-T→CNR② FREQ→Channel→27② FREQ→Channel→27

(1/7MHz offset :ISDB-T mode)③ FUNC→Noise (Out of Band)

Noise F1=550MHz , Noise F2= on, Mesurment Frequency =551MHz ,RETURN Noise F3= on Mesurment Frequency =561MHz RETURNNoise F3= on, Mesurment Frequency =561MHz ,RETURN Noise F4= on, Mesurment Frequency =562MHz, RETURN

④ Average Times = 10→ENTER⑤⑤ Noise Correction→On

・Tokyo ISDB-T-channelTokyo ISDB T channel18ch(MHz)～28ch(MHz) 27

Resultado de la Medición de CNR

28

Medicion de “Tasa del Error de señal"

Medición de BER(BER: Bit Error Rate)

29

Bit Error Rate Measurement Methods

■ In digital broadcasting, it is difficult to do the kind of image quality evaluation done in analog broadcasting, so image quality is evaluated by the bit error rate (BER) which is the ratio of error bits to the total bitsthe bit error rate (BER), which is the ratio of error bits to the total bits in the demodulated 0 and 1 digital signal. In digital broadcasting, the BER is measured before and after inner code (convolution) correction. Wh th i d l ti h i 64QAM if th BER i 1 10 2When the carrier modulation scheme is 64QAM, if the BER is 1×10-2 or less before or 2×10-4 or less after inner code correction, then it is 1×10-

11 or less after RS decoding (outer code correction), which is virtually error free, and good reception is possible.

(Transmitter and receiver parts relevant to signal quality)

( )

Video&AudioMPEG encoding

Multi-plexing

Error correctedouter codeinner code

Digital MODOFDM Signal transmission

OFDM signal(UHF signal)

(Transmitter)

Tuner A / D

OFDM signal(UHF signal) (Receiver) Error correction

RSViterbid di

Demodulated Vid &A di

30通常は内符号訂正後（RS復号前）のBERを測定する※このとき、所要BERは2×10-4となる

decodingdecoding

BER measurement

Video &Audiooutput

BER is usually measured after Viterbi-decoding(Required BER is 2x10-4 at the point )

Medición de BER

（１） PRBS measurement( )

Measuring with(PRBS:Pseudo Random Binary Sequence)

（２） Sync＋PRBS measurementBER counter

（３） NULL Packet measurement

Pre-Viterbi

RF

Post-RS

SAWFilter

A/D Quadra-ture

demod

FFT/sync

Detector De-interleav

e

Viterbidecoding

TSRegene-

rate

RSdecoding

RFinput

TSPt t

Post-Viterbi Pre-RS

output

31

Método de Mediciõn de Null Paket

■Null Packet measurement

Mostreo de paqute nuloMPEG TS OFDM

modVia de

transmisionOFDMdemod

TS

Medicion de la tasa de error

comparativo de bit

Con el ajuste de tasa se introduce el paquete nulo y se dispersan de energia e i t l

No.Bits medidos

No. Bits erroneosBER=

Null Packet

interleave

Header Payload (Null)

4 byte 184 byte 16 byte

Dummy

Null Packet

PID FFF

32

PID=1FFF

Medición de BER

［Entrenando-3］ BER mesurement［Entrenando-3］ BER mesurement

■［3-1］On-Air signal■［3 ］O s g a① CONFIG→ISDT-T→FREQ→Channel→27② FUNC→BER→BER Type→Null ③③ Packet → Display =BER④ Measurement Time=3sec

■［3-2］SG signal (C/N=20.1dB)

33

Resultado de la Medición de BER

■Measuring On-Air signal

34

Resultado de la Medición de BER

■Measuring SG OutPut (C/N=20.1dB)

35

CNR vs BER Curve

Post-Viterbi

Layer A Layer B

36

Tasa de CN necesaria de cada esquema de la transmisión

Convolutional Coding Rate

単位:[dB] 7/85/63/42/31/2

Convolutional Coding RateCarrier

modulation 7/83/42/31/2

(9.1)(8.5)(7.5)6.64.9QPSK

(16.2)(15.6)(14.6)13.511.516QAM

(9.1)(8.5)(7.5)6.64.9QPSK

(16.2)(15.6)(14.6)13.511.516QAM

22.021.320.118.716.564QAM 22.021.320.118.716.564QAM

37

Medición de “Tasa del Error de Señal"

Medición de MER(MER: Modulation Error Ratio)

38

Definición de MER

■Modulation error ratio (MER)MER is the power ratio of the vectors extending from the ideal

( )symbol positions of a constellation (ideal constellation points) to the received symbol positions (symbol error vectors) converted topower values to the ideal constellation. MER is defined as

理想コンスタレーション

ポイント

受信シンボルベクトル誤差

symbol error vector Ideal constellation point

received symbol

pshown below.

δI

δQQ

∑N

QI 22 )(

理想シンボルベクトル

IIdeal constellationvector

∑

∑=

+

+×=

Nk

kk

QI

QIMER

22

1

22

10

)(

)(log10[dB]

δδ

39

∑=

+k

kk QI1

)( δδ

Gráfica de Correlación MER－CN (Example)

■The constant correlation between MER and and CN ratio means that knowing the relationship of MER and CN ratio allowsmeans that knowing the relationship of MER and CN ratio allows estimation of the CN ratio and BER from the MER.

40Non-linearity due to d d l ti

30MER

[dB

]

Non-linearity due to themeasurement system noise floor

Linear region

demodulation error

2020 30 40 50

20

CN[dB]

40

In the linear region, this graph can be used for direct MER－CN conversion

Medición de MER

［Entrenando-4］MER measurement

■［4-1］On-Air signal

① CONFIG→ISDT-T→FREQ→Channel→27② FUNC→More2/2→MER CONSTELLATION③③ Layer→All,A,B,TMCC,AC

■［4-2］add SG Noise■［4-2］add SG Noise（Reference）① FUNC→More2/2→MER vs SEGMENT① FUNC→More2/2→MER vs SEGMENT② FUNC→More2/2→MER vs CARRIER

41

Resultado de la Medición de MER■On Air signal

Layer A

42Layer B

Resultado de la Medición de MER■add SG Noise

Layer A

43Layer B


Medición de multipassMedición de multipass

44

Principio de multipass

Undesired echo Scattered PilotScattered Pilot

Desiredwave

(On-Air)synthesized

signal Transmitter

Delay Profile

Delay timeDU ti

Corelation Operating

Receiver DU ratioReceiver

45

Effect of multipath propagation on terrestrial digital broadcast

■Multipath and rippleThe signal delay introduced by a multipath environment inThe signal delay introduced by a multipath environment in

terrestrial digital broadcasting creates in-band deviation (ripple) in the amplitude frequency characteristic waveform andBER i d d dBER is degraded. The multipath DU ratio and and the amplitude frequency characteristic wave form ripple are related as follows.

1

■Relation of delay time τ and ripple amplitude ∆L

レベ

D/U=3dBτ=0.5μs

レベレベ

D/U=3dBτ=0.5μs

τ1

UD +UD + ⎟⎞

⎜⎜⎛

+= ∆

∆

110log20[dB]20

10 L

L

DU(dB

)

ベル

(dB）

ベル

(dB）

ベル

(dB）

UD −UD −

ΔLΔL⎠

⎜⎜

⎝ −∆

110g[ ]

2010 L

leve

l

46周波数(MHz）

5dB1MHz

周波数(MHz）

5dB1MHz

周波数(MHz）

5dB1MHz

Frequency (MHz)

Medición de multipass

［Entrenando 5-1］Multipath measuring by Spectrum Analyzer mode

① Shift + PRESET② CONFIG → Spectrum Analyzer③ Center→557.142856MHz

(UHF 27ch+0.142856MHz offset)④ S 0MH BW RBW M 30kH④ Span→10MHz, BW→RBW→Man→30kHz ,

VBW→Man→300kHz⑤ SWEEP → Man → 100ms⑤ SWEEP → Man → 100ms⑥ LEVEL → to Screen Center⑦ TRACE → Max Hold⑧ MKR → PEAK → Delta Marker

→ Next PEAK → Read MKR∆⑨ D l Ti 1/[MKR∆] ( )MH ( )

47

⑨ Delay Time = 1/[MKR∆] = ( )MHz = ( ) µs⑩ Read D/U on screen ( dB)

Resultado de la Medición de multipass

■La medida de multipass por modo de analizador de Espectro

⎞⎜⎛ ∆

110 20L

⎟⎟

⎠⎜⎜⎜

⎝ −

+= ∆

110

110log20[dB]20

20

10 LDU

1τ

UD +UD +

UD −UD −ΔLΔL

48

Delay Profile Measurement Principle

• The CP and SP of the signal whose amplitude and frequency (carrier number), and phase are known in advance are embedded in the OFDM signal), p g– CP: Continuous pilot– SP: Scattered pilot

Th i d CP d SP di id d b th t itt d CP d SP (k )• The received CP and SP are divided by the transmitted CP and SP (known) for each carrier and the transmission path frequency characteristic can be estimated by interpolation. ω: angular frequency – H(ω)＝R(ω) / S(ω)

• By applying the inverse Fourier transform to H(ω), the delay profile is bt i dobtained. – H(ω): Estimated transmission path frequency characteristic

• The signal that has maximum amplitude in the delay profile is taken as the• The signal that has maximum amplitude in the delay profile is taken as the desired signal. – IFFT: Inverse FFT

h(ｔ)=IFFT(H(ω))

Measurement of Delay Profile

［Entrenando 5-2］Multipath measuring by Delay Profile mode

① CONFIG→ISDT-T→FREQ→Channel→27② FUNC→MULTI PATH

→Desired Wave Position=25%③ Smoothing=on④ Zoom=on, Window Width=10µs

MKR → Marker 2 =On → Read MKR(2)※MKR（1）：Desired wave

50

Resultado de la Medición de multipass

51


E i l t C i t N iEquivalent Carrier to Noise,Equivalent Noise DegradationEquivalent Noise Degradation,

Noise Mergin

52

END, ECN & Noise Margin

■ E i l t CN ti (ECN)■ Equivalent CN ratio (ECN)

is the value of the degradation of various transmission equipment and transmission path characteristics converted to Gaussian noise.

■Can be obtained with the following equation, using the amount of equivalent CN ratio degradation obtained from th diff f th CN ti f hi h dthe difference of the CN ratio for which produces Gaussian noise (ideal characteristic) that corresponds to the required BER and the CN ratio of the transmissionthe required BER and the CN ratio of the transmission path characteristics.

53

END, ECN & Noise Margin

ER

64QAMencoding rate=3/4

BE

ＥＮＤＮoise Ｍargin

Required BER

Transmission2×10-4 Transmission path

characteristic

Idealcharacteristic No Noise

addition

CNR[dB]20.1 CNa MeasuredCNR

54

CNR)1010(log10CN 10/10/1.20

10aCNE −− −×−=

END vs ECN

6

7

8

5

6

D (dB)

3

4

END

Measurement

1

2Measurementlimit

approx. 37dB

0

20 22 24 26 28 30 32 34 36 38 40 42

ECN (dB)

55

Medición de END、 Proporción de CN equivalente 、Margen del ruido

［ Entrenando -6］Equivalent CN analysys

①① CONFIG→ISDT-T→FREQ→Channel→27② FUNC→More2/2→BER vs CNR CURVE③ Step CNR=0.5dB④ Measuerment Time=1sec⑤ Reference BER=2E-4⑥ CNR Step→Noise (out-band)

N i F 550MH N i F2 55 MHNoise F1=550MHz , Noise F2= 551MHz ,Noise F3=561MHz ,Noise F4=562MHz

⑦ Noise Correction→On⑦ Noise Correction→On⑧ Layer = B⑨ Noise Add Mode = Exc

56

⑨ Noise Add Mode Exc

Equivalent C/N、END、NM measurement

BER vs C/N

Required C/N(20 1dB)

Measure automaticallyEND

Required C/N(20.1dB)Reference Curve

57

Resultado de la Medición(1)

（例）C/N(25.89)-NM(4.44)-END(1.35)=20.1dB（例）NM（NM=2.24）=C/N(25.84)-END(3.50)-20.1

C/N=25dB,τ=0.5µsec,D/U=10dB

58C/N=35dB,τ=0.5µsec,D/U=6dB

Resultado de la Medición(2)

C/N=25dB,τ=0.5µsec,D/U=10dB

59C/N=35dB,τ=0.5µsec,D/U=10dB

ReferenciaReferencia

60

Ondas de OFDM y parámetro de la transmisión13 segment

1/7MHz(≒0.143MHz)

Continual Pilot carrier at the uppermost freq.

14 segment

SHIFT

モード Mode-1 Mode-2 Mode-3

Bandwidth 〔kHz〕 6MHz / 14 = 428.57...Spacing between

i f i 〔〕250 / 63

3 968125 / 63

98125 / 126

0 99206carrier frequencies 〔kHz〕 = 3.968… = 1.9841… = 0.99206…Number of carriers 1,405 2,809 5,617Carrier modulation scheme 16QAM、64QAM、QPSK、DQPSK

Guard interval 〔µs〕

63(1/4)31.5(1/8)15.75（1/16)7.875(1/32)

126(1/4)63(1/8)31.5(1/16)15.75(1/32)

252(1/4)126(1/8)63(1/16)31.5(1/32)

61

IFFT sampling freq〔MHz〕 512 / 63 = 8.12693…

Block Diagram of ISDB-T tuner unit (example)

ARIB STD-B21 4.6 p.14 Outline of a receiving block diagram 62

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