Mer Graficas

8/17/2019 Mer Graficas

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El entrenamiento Radiodifusión digital terrestre

Varias mediciones de radiodifusión digital terrestre

24 d f b d 20104 de febrero de 2010

NHK Engineering Administration Department

Ritsuko Okabe

1

Ritsuko Okabe


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

Cause of De radation

symptom

Analo Di ital

NTSC-AM) (OFDM)

Weak signal strength

Picture break u

CN Ratio degradation

Multipath echo Ghosting

or freezing No reception

Adjacent channel interferencePatterns on the

CW, booster oscillation

IM,CTB

Electrical interference Dots, flashes

In digital broadcasting …

S m tom is the same, re ardless of interference t e

2Rapid image degradation below threshold Cliff Effect


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Measurement of Digital Terrestrial TV

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4


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Measurement of Digital Terrestrial TV

Signal strength

Channel power dBmW

RF signal quality

arr er to o se at o

Demodulated signal quality

MER Modulation Error Ratio

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5


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Referencia Un diagrama del Sistema

On-Air

TS

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Analizador de Señal Digital TV

Keys on the Panel(Hard Key)

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Base de Operación

Select standardONFIG

requency se ngREQ

Function settingUNC

10 Key Unit

8

Start


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9


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Preparación de la Medición

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Menu Overview

CONFIG FREQ FUNC

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MEAS. SETUP

ISDB-T mode settin Default Value:3

FUNC

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

Mode setting

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Measurement Modes

FeaturesUsageISDB-Tmeasurement

High MER measurement (MER>50dB)

Ranging is done only at the start; Auto

Single channel output for

transmitter / repeater (signal

Transmitter

mo e

Range processing is not donequality is high and stable).

measurement to deal with levelfluctuations

-

with little effect of multipathecho and other interference.

Post-Viterbi BER 2E-4(CR 7/8,64QAM)

can be measured under following

Multi-channel transmission

under effect of multipath

Field

emv ronmen .

-low electric field (40dBµV)

-multipath (D/U 0dB)

Auto Ran e rocessin is done durin

ec o an o er n er erence

which prevent measurement

in Normal mode

measurement


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Checking Noise Floor

ATT set to optimum value

LEVEL

Incorrect ResultMin ATT

Auto Level

ATT set to low value,re mp urne n

Correct Result

Preamp set to On

On Off


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Medición de "Fuerza de Señal"

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Medición de la Potencia de Canales

Channel Power Mesurement

o a power measuremen n e an

Able to measure accurate power of the signal which-

Parameter of Spectrum AnalyzerParameter

Band Width 5.6MHz

Resolution Band Width 30kHz

Detection Mode Sample

Averaging 30times

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E t d 1

Medición de la Potencia de Canales (13Seg)

Entrenando-1Measurement of 13 Segment Channel Power by

[CONFIG]→ Spectrum Analyzer

.

(UHF27ch+0.142856MHz offset)

[BW]→RBW→Man→30kHz, VBW→Man→300kHz

LEVEL→ to Screen Center

→ anne ower→ n ow=on

Window Width→5.6MHz

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n er creen = m

(Unit change LEVEL→Units→dBu,dBm)


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Channel Power measurement

Spectrum Analyzer mode

→ anne ower→ n ow z

Equivalent from 13segment Channel Power value

characteristics in 5.6MHz band → flat

1seg Power=13seg Power – 11.14dB (=10log(1/13))

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Entrenando-1

Measurement of 1Segment Channel Power bySpectrum Analyzer Mode

[Center]→557.142856MHz

.

[Span]→1MHz

,

[SWEEP]→Man→100ms

Window Width→429kHz

21Under Screen C= dBm(RMS)


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Indicacion de la Intensidad del campo eléctrico

Information

Channel, Center freq.

St d d Ch Ptandard, Ch Power

Result

Bar Graphar Graph

read “average” value

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Medida de "Calidad de signo"

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Definición de CNR

in OFDM band width(5.57MHz)

Average Carrier level Crms[V]

= rms rmsdB(V)=20log10 (V)

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Medición la Tasa de CN

Entrenando-2 CNR mesurement

CONFIG→ISDB-T→CNR

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

Noise F1=550MHz ,Noise F2= on, Mesurment Frequency =551MHz ,RETURN, ,

Noise F4= on, Mesurment Frequency =562MHz, RETURN

Average Times = 10→

ENTERNoise Correction→On

- -

18ch(MHz) 28ch(MHz) 27


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Resultado de la Medición de CNR

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Medicion de “Tasa del Error de señal"

Medición de BER

(BER: Bit Error Rate)

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In digital broadcasting, it is difficult to do the kind of image qualityevaluation done in analog broadcasting, so image quality is evaluated by

,

in the demodulated 0 and 1 digital signal. In digital broadcasting, the

BER is measured before and after inner code (convolution) correction.en t e carr er mo u at on sc eme s , t e s - 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

RS Viterbi Demodulated

30RS BER

BER 2 10-4

decodingdecoding

BER measurement

Video &Audiooutput

BER is usually measured after Viterbi-decoding

Required BER is 2x10

-4

at the point )


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Medición de BER

PRBS measurementMeasuring with

PRBS:Pseudo Random Binary Sequence

Sync PRBS measurement

BER counter

NULL Packet measurement

Pre-Viterbi

RF

Post-RS

SAW

Filter

A/D Quadra-

ture

demod

FFT/

sync

Detector De-

interleav

e

Viterbi

decoding

TS

Regene-

rate

RS

decoding

RF

input

TSP

t t

Post-Viterbi Pre-RS

output

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Método de Mediciõn de Null Paket

Null Packet measurement

Mostreo de

paqute nulo

PEG TS

OFDM

mod

Via de

transmision

OFDM

demod

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 erroneos

BER=

Null Packet

interleave

Header Payload Null)

4 byte

184 byte

16 byte

Dummy

Null Packet

PID FFF

32

PID=1FFF


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Resultado de la Medición de BER

Measuring On-Air signal

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R l d d l M di ió d BER


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Resultado de la Medición de BER

Measuring SG OutPut (C/N=20.1dB)

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CNR BER C


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CNR vs BER Curve

Post-Viterbi

Layer A Layer B

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Tasa de CN necesaria de cada esquema de la transmisión

:[dB] 7/85/63/42/31/2

onvo u ona o ng a eCarrier

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

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M di ió d “T d l E d S ñ l"


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Medición de “Tasa del Error de Señal"

Medición de MER

(MER: Modulation Error Ratio)

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D fi i ió d MER


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Definición de MER

MER is the power ratio of the vectors extending from the idealsymbol positions of a constellation ideal constellation points tothe received symbol positions (symbol error vectors) converted to

power values to the ideal constellation. MER is defined asshown below.

I

QQ

N

I

=

+

×= N

k

k k Q I

MER22

1

10

)(

log10[dB]

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=k k k

1

G áfi d C l ió MER CN (E l )


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Gráfica de Correlación MER CN (Example)

The constant correlation between MER and and CN ratio

estimation of the CN ratio and BER from the MER.

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Non-linearity due to

30 M E R [

d B ]

Non-linearity due to the

measurement system noise floor Linear region

emo u a on error

20 30 40 50

CN[dB]

40

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

Medición de MER


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Medición de MER

Entrenando-4 MER measurement

4-1 On-Air signalCONFIG→ISDT-T→FREQ→Channel→27FUNC→More2/2→MER CONSTELLATIONLayer→ All,A,B,TMCC,AC

-

Reference

FUNC→More2/2→MER vs CARRIER

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Resultado de la Medición de MER


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On Air signal

Layer A

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Layer B



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add SG Noise

Layer A

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Layer B



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Medición de Tasa del Error de Señal

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Principio de multipass


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Principio de multipass

Undesired

echo

Desiredwave

(On-Air)synthesizedsignal

TransmitterDelay Profile

Delay time ra o

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Effect of multipath propagation on terrestrial digital broadcast


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Effect of multipath propagation on terrestrial digital broadcast

Multipath and ripple

terrestrial digital broadcasting creates in-band deviation

(ripple) in the amplitude frequency characteristic waveform ands egra e .The multipath DU ratio and and the amplitude frequencycharacteristic wave form ripple are related as follows.

Relation of delay time τ and ripple amplitude ∆L

D/U=3dB

=0.5 s

D/U=3dB

=0.5 sτ

U D +U D + ⎟ ⎞

⎜⎛

+

=

∆

110

lo20dB

20

L

DU ( d B )

(dB(dB(dB

U D −U D −

L L

⎠⎜⎝ −110

20 l e v e l

46(MHz

5dB1MHz

(MHz

5dB1MHz

(MHz

5dB1MHz

Frequency (MHz)


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Delay Profile Measurement Principle


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Delay Profile Measurement Principle

• The CP and SP of the signal whose amplitude and frequency (carrier

number and hase are known in advance are embedded in the OFDM si nal

– CP: Continuous pilot

– SP: Scattered pilot

• e rece ve an are v e y e ransm e an nown

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

o a ne .

– H(ω): Estimated transmission path frequency characteristic

desired signal.

– IFFT: Inverse FFT

h( )=IFFT(H(ω))

Measurement of Delay Profile


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y

Entrenando 5-2

Multipath measuring by Delay Profile mode

CONFIG→ISDT-T→FREQ→Channel→27

FUNC→MULTI PATH

→Desired Wave Position=25%

Smoothing=on

Zoom=on, Window Width=10µs

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

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Resultado de la Medición de multipass


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es a o e a e c ó e pass

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qu va en arr er o o se,

,

Noise Mergin

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END, ECN & Noise Margin


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, C & o se a g

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END, ECN & Noise Margin


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, g

R

64QAMencoding rate=3/4

B

Required

BER

Transmission

2 10

-4

Transmission

path

characteristic

Ideal

characteristic

No Noise

addition

CNR[dB]0.1 CNa

Measured

CNR

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CNR

)1010(log10CN10/10/1.20

10aCN E

−− −×−=

END vs ECN


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Medición de END Proporción de CN equivalente Margendel ruido


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del ruido

Entrenando -6 Equivalent CN analysys

CONFIG→ISDT-T→FREQ→Channel→27

FUNC→More2/2→BER vs CNR CURVE

Step CNR=0.5dB

Measuerment Time=1sec

Reference BER=2E-4

CNR Step→Noise (out-band)o se 1= z , o se = 1 z ,

Noise F3=561MHz ,Noise F4=562MHz

Layer = B

=

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Equivalent C/N END NM measurement


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q

BER vs C/NMeasure

automaticallyEND

.Reference Curve

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Resultado de la Medición(1)


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

C/N=25dB,τ=0.5µsec,D/U=10dB

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Resultado de la Medición(2)


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Ondas de OFDM y parámetro de la transmisión


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Mode-1 Mode-2 Mode-3

Bandwidth kHz6MHz / 14 = 428.57...

Spacing between250 / 63

3 968

125 / 63

98

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0 99206carrier frequencies kHz= 3.968…

= 1.9841…

= 0.99206…

Number of carriers1,405

2,809

5,617

Carrier modulation scheme16QAM 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)

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IFFT sampling freq MHz 512 / 63 = 8.12693…

Block Diagram of ISDB-T tuner unit (example)


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