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Digital Television Broadcasting Systems

Testing in Brazil

Kiev, Ukraine - 13-15 November 2000

Interregional Seminar on the Transition from SECAM to Digital TV Broadcasting

Renato Maroja - maroja@cpqd.com.br

Fundação CPqD - www.cpqd.com.br

Campinas - SP - Brazil

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Organization of the tests

• Entities and roles– ANATEL - National Agency of Telecommunications - Brazilian regulating

authority• Conducts the process of defining a DTV standard for Brazil• Authorized (after a public consultation) the realization of the field tests• Contracted CPqD as consultant in the process• Will define the DTV standard based on the tests results and other technical and

non-technical aspects

– SET - (Brazilian) Society of Television Engineering

– ABERT - Brazilian Association of Radio and Television Broadcasters• SET/ABERT studies the evolution of DTV standards since 1994, and has

structured task groups to carry on the tests• Makes planning studies to consider digital channels along with analog channels• Technological agreement with Instituto Mackenzie - Human resources

– Instituto Mackenzie - a Brazilian private University, in São Paulo• Tests methodologies• Acquired test equipment, set up the laboratory and field tests installations• Executed the tests and reported the results to ANATEL, together with

SET/ABERT

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• Entities and roles (cont)– CPqD - Private foundation with expertise in Telecommunications

• support in systems aspects - CPqD works in multiple areas in telecommunications

• analysis and consolidation of the laboratory tests methodology• development of ambiences for systems simulations• analysis and consolidation of the field tests methodology• checking and support in the laboratory and field tests• development of tools for planning studies• analysis of the tests results • advice on other aspects of the introduction of Digital TV in Brazil

Organization of the tests

~1100 employees600 000 m2

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Laboratory and Field Tests

• Tests objectives: Compare terrestrial DTV systems with respect to the transmission layer

• Laboratory Tests - robustness/capacity analysis of the systems under controlled conditions

– Interference - A to D, D to A, D to D, CW and FM: planning

– Robustness to impulsive noise

– Multipath performance• static, single and multiple echoes• dynamic, Doppler shift, mobility

– BER x C/N performance in white noise (AWGN) - modulation, planning, transmitter power

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Interference: Protection Ratios

Digital into Analogue (*) ATSC DVB - 2K DVB - 8K ISDBCo-channel 37 38 38 38Upper adjacent -9 -9 -9 -9Lower adjacent -7 -7 -7 -11Analogue into Digital ATSC DVB - 2K DVB - 8K ISDBCo-channel 5 7 7 6Upper adjacent -32 -31 -26 -34Lower adjacent -40 -27 -32 -34Digital into Digital ATSC DVB - 2K DVB - 8K ISDBCo-channel 15 20 20 18Upper adjacent -27 -25 -25 -29Lower adjacent -27 -25 -24 -24

(*) CCIR 4: 37,5 dBTaboo channels interference: irrelevant

D/U = Desired/Undesired Signal power ratio (dB)Lower ratios more robustness

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Robusteness to Impulsive Noise

-30

-25

-20

-15

-10

-5

0

5

10

15

0,0 100,0 200,0 300,0 400,0 500,0 600,0 700,0 800,0 900,0

Window (s)

C/Neq(dB)

ATSC - Zenith

ATSC - Chip T

ATSC - Chip S

ATSC - Chip A

DVB 3/4 1/16 2K

DVB 3/4 1/16 8K

DVB 3/4 1/8 2K

DVB 2/3 1/32 8K

DVB - Chip N - 3/4 1/16 2K

DVB - Chip N - 2/3 1/32 8K

DVB - Chip M - 2/3 1/32 8K

DVB - Chip L 2/3 1/32 8k

DVB - Chip L 3/4 1/16 8k

ISDB 3/4 1/16 4K INT4

ISDB - Chip J

C/N

eq

(dB

)

Digital signal + gated Noise C/NeqGate: 30s cycle, 12,5 Hz to 100 Hz, fixed TW

BER < 3 x 10-6 within 2 minutes counting

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Multipath - single static echo

Gráfico 3.1.3.4: Relação entre o atraso e a relação eco-sinal para taxa de erro de limiar

-25

-20

-15

-10

-5

0

5

-160 -120 -80 -40 0 40 80 120 160Atraso (em us)

E/C

(dB

)

ATSC

ATSC - Chip S

DVB 3/4 1/16 2K

DVB - Chip M - 3/4 1/16 8K

DVB - Chip M - 2/3 1/32 8K

ISDB 3/4 1/16 4K 0,1s

ISDB - Chip J

Echo delay (s)

tG = 74 s

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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C/N degradation with single echo

C/N

(d

B)

•Increased echo amplitude requires higher C/N (imposes penalty)•DVB-T and ISDB demodulators showed evolution along the tests•COFDM: guard interval•ATSC cannot stand strong echoes: ~2 dB with high penalties•8VSB: (long, complex) transversal equalizers

tG = 18,7 s

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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BER x C/N performance

C/N @ BER = 3 x 10-6

•ATSC Zenith: 14.5 dB•DVB-T chip M 2/3 1/32 8K: 16.9 dB @ LOP•DVB-T NDS 3/4 1/8 2K: 18.8 dB•ISDB-T DiBEG 3/4 1/16 2K/4K/8K: 18.5 dB

COFDM: robustness x payload

Better - Worse Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Field Tests

• Field tests - robustness/capacity analysis under real reception conditions– Coverage - real world reception includes white noise, multipath,

interference from other channels and impulsive noise

– Gap filler - recover coverage on a shadowed spot

– Indoor reception - high attenuation and time varying multipath

– Mobility - Doppler frequency shift - some trajects in São Paulo, near the transmitter

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Field Tests - TX Site

• São Paulo– Biggest market in Brazil: 40% GNP

– Economical potential

– "Acid test": difficult coverage• Topographic conditions - gap filler• High density of buildings in some regions

– UHF channel 34 (593 Hz center frequency)

• TX station– Site definition for TV Cultura tower: coverage, infrastructure and space

for equipments and for antenna in tower

– Transmitter: Harris DCD20PL1, operated at 2,5 KW for all systems

– Antenna: 104 m agl; 9.3 dBd; 12 KW max. ERP

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Field Tests - RX Site

• RX Van• mast 10 m agl• Antenna: Scaffner, 2.6 dBd• Pre-amplifier, hybrids• Noise Generator• Receivers - availability• MPEG 3 Decoder• Spectrum Analyzer

Measurement period: Nov 9, 1999 to Abril 28, 2000

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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RX Test sites in São Paulo

Measurement Procedure•Point RX antenna to obtain best reception•Measure received C/N @ C = -30 dBm•Add external noise up to BER Threshold or artifacts; •Calculate available margin, electric field,etc

C = Signal PowerN = Noise power in channel bandwidthC/N = Signal to noise ratio

Measured points•17 radials 15o apart•distances: 3, 6, 9, 12, 15, 20, 25, 30, 40 Km

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III.3.1.4.7 Percentual de Recepção - Gráfico por DistânciaCritério: Margem > 0

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

3 6 9 12 15 20 25 30 40

Distância (km)

Pe

rce

ntu

al

de

Sit

es

ATSC DVB - 8k DVB - 2k ISDB - 4k

Distance (Km)

Per

cen

tag

e o

f si

tes

Field Tests - Coverage

Criterion: Margin > 0 dB

127 test points: ATSC and DVB-T 2K

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Field Tests - Coverage

III.3.1.4.8 Percentual de Recepção - Função CumulativaCrtério: Margem > 0

60%

70%

80%

90%

100%

0 5 10 15 20 25 30 35 40

Distância (km)

Pe

rce

ntu

al

de

Sit

e

ATSC DVB - 2k DVB - 8k ISDB - 4k Canal VHF-Alto/Analog. 3 a 5 Canal VHF-Alto/Analog. 2 a 5

Distance (Km)

Per

cen

tag

e o

f si

tes

Criterion: Margin > 0 dB

127 test points: ATSC and DVB-T 2K

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Field Tests - Coverage

III.3.1.5.7 Percentual de Recepção - Gráfico por Distância - 27 Pontos SimutâneosCritério: Margem > 0

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

3 6 9 12 15 20 25 30

Distância (km)

Pe

rce

ntu

al

de

Sit

e

ATSC DVB 8K 2/3 1/32 DVB 8K 3/4 1/16 DVB 2K 3/4 1/16 ISDB 4K 3/4 1/16

Distance (Km)

Per

cen

tag

e o

f si

tes

Criterion: Margin > 0 dB

27 test points: ATSC, DVB-T 2K,

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Field Tests - Coverage

III.3.1.5.8 Percentual de Recepção - Função Cumulativa - 27 Pontos SimutâneosCritério: Margem > 0

30%

40%

50%

60%

70%

80%

90%

100%

0 5 10 15 20 25 30

Distância (km)

Pe

rce

ntu

al

de

Sit

es

ATSC DVB 8K 2/3 1/32 DVB 2K 3/4 1/16 DVB 8K 3/4 1/16 ISDB 4K 3/4 1/16

Distance (Km)

Per

cen

tag

e o

f si

tes

Criterion: Margin > 0 dB

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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LOCALIZAÇÃO DOS PONTOS DE MEDIDASGAP FILLER

1 2 33

8

14 1615

36

27

31 37 38

26 40 41

39

17

44

9 10 11 12

45

18 19

65

43

35 1334333220

21 22

30 29

24

44

500m 1000m 1500m 2000m 2500m 3000m

500m

1000m

1500m

2500m

PONTOS DE ATUAÇÃO DO GAP FILLER

PONTOS DE SOBREPOSIÇÃO DE SINAIS DA ESTAÇÃO PRINCIPAL E O GAP FILLER

PONTOS FORA DA AREA DE ATUAÇÃO DO GAP FILLER

13

1000m

1500m

2000m

2000m

2500m

3000m

3500m

46

ActuationSuperpositionOut of range

Gap filler measurement sites

•Gap filler Radiation pattern•Tilted beam

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Outdoor Reception - Gap Filler

Superposition region

27%

45%

82% 82%

73%

91%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

OFF ON

ATSC DVB-8K ISDB-8K

Actuation region

23%

85%77%

100%

77%

100%

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

OFF ON

ATSC DVB-8K ISDB-8K

Improvement of reception with gap fillerAntenna is re-oriented with gap filler on/offDistance from main transmitter ~5,6 Km -> ~19 s

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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Indoor Reception

Normal Blender On People walking around near antenna

Per

cen

tage

of

good

rec

epti

on

12 sites where the 3 systems were tested under identical conditions

Indoor antenna: UHF log-periodic - Silver Sensor

Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000

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SET/ABERT Reports

The data, tables and graphs presented here were extracted mainly from the SET/ABERT Final Report - Part 2, that is available in Portuguese and in English at: www.anatel.gov.br

These results express the conclusions arrived at by SET/ABERT, and do no express ANATEL's viewpoint.

Thank you for your attention