El entrenamiento Radiodifusión digital...
Transcript of El entrenamiento Radiodifusión digital...
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
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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
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◆ 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)
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PrácticaPráctica
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(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
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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
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Preparación de la Medición
Initialization
Calibration
MEAS. SETUP setting
◆ISDB-T mode settingg
◆MEAS Mode setting
ATT iATT setting
Pre Amp setting
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Inicialización
MENU
Special
Preset All Initialize all parameters[Default mode][Default mode]ISDB-T Channel PowerATT=10dB, Pre-amp Off
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Menu Overview
CONFIG FREQ FUNC
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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%
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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
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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
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[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)
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⑨ Under Screen C= dBm(RMS) (Unit change :LEVEL→Units→dBu,dBm)
Medición de la Potencia de Canales (13Seg)
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Medición de la Potencia de Canales (1Seg)
■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))
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Medición de la Potencia de Canales (1Seg)
[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)
Medición de la Potencia de Canales (1Seg)
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Intensidad del campo eléctricoIntensidad del campo eléctrico
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Indicacion de la Intensidad del campo eléctrico
■InformationChannel, Center freq.St d d Ch PStandard, Ch Power■Result
Bar GraphBar Graphread “average” value
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Medida de "Calidad de signo"
Medición la Tasa de CNMedición la Tasa de CN
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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)】
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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
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Medicion de “Tasa del Error de señal"
Medición de BER(BER: Bit Error Rate)
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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
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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
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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)
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Resultado de la Medición de BER
■Measuring On-Air signal
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Resultado de la Medición de BER
■Measuring SG OutPut (C/N=20.1dB)
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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
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
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Medición de “Tasa del Error de Señal"
Medición de MER(MER: Modulation Error Ratio)
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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
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1
22
10
)(
)(log10[dB]
δδ
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∑=
+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]
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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
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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 “Tasa del Error de Señal"
Medición de multipassMedición de multipass
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Principio de multipass
Undesired echo Scattered PilotScattered Pilot
Desiredwave
(On-Air)synthesized
signal Transmitter
Delay Profile
Delay timeDU ti
Corelation Operating
Receiver DU ratioReceiver
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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.
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■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 ( )
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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
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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
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Resultado de la Medición de multipass
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Medición de “Tasa del Error de Señal"
E i l t C i t N iEquivalent Carrier to Noise,Equivalent Noise DegradationEquivalent Noise Degradation,
Noise Mergin
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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.
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END, ECN & Noise Margin
ER
64QAMencoding rate=3/4
BE
END Noise Margin
Required BER
Transmission2×10-4 Transmission path
characteristic
Idealcharacteristic No Noise
addition
CNR[dB]20.1 CNa MeasuredCNR
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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)
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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
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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
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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
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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)
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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