Digital Television Broadcasting Systems Testing in Brazil Renato Maroja - maroja@cpqd.com.br Fundação CPqD - www.cpqd.com.br Campinas - SP - Brazil 1 Copyright by CPqD©- 2000 Kiev, Ukraine - 13-15 November 2000 Interregional Seminar on the Transition from SECAM to Digital TV Broadcasting 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 – 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 2 Copyright by CPqD©- 2000 • 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 Organization of the tests • Entities and roles (cont) – CPqD - Private foundation with expertise in Telecommunications ~1100 employees 600 000 m2 3 Copyright by CPqD©- 2000 • 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 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 4 Copyright by CPqD©- 2000 – BER x C/N performance in white noise (AWGN) - modulation, planning, transmitter power Interference: Protection Ratios D/U = Desired/Undesired Signal power ratio (dB) Lower ratios ⇒ more robustness Digital into Analogue (*) Co-channel Upper adjacent Lower adjacent Analogue into Digital Co-channel Upper adjacent Lower adjacent Digital into Digital Co-channel Upper adjacent Lower adjacent ATSC 37 -9 -7 ATSC 5 -32 -40 ATSC 15 -27 -27 DVB - 2K DVB - 8K 38 38 -9 -9 -7 -7 DVB - 2K DVB - 8K 7 7 -31 -26 -27 -32 DVB - 2K DVB - 8K 20 20 -25 -25 -25 -24 ISDB 38 -9 -11 ISDB 6 -34 -34 ISDB 18 -29 -24 5 Copyright by CPqD©- 2000 (*) CCIR 4: 37,5 dB Taboo channels interference: irrelevant Robusteness to Impulsive Noise Digital signal + gated Noise ⇒ C/Neq Gate: 30s cycle, 12,5 Hz to 100 Hz, fixed TW BER < 3 x 10-6 within 2 minutes counting ATSC - Zenith 15 ATSC - Chip T 10 ATSC - Chip S ATSC - Chip A 5 DVB 3/4 1/16 2K 0 C/ Ne -5 q (d -10 B) -15 C/Neq(dB) 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 -20 DVB - Chip L 3/4 1/16 8k -25 ISDB - Chip J -30 0,0 100,0 200,0 300,0 400,0 500,0 Window (µs) 600,0 700,0 800,0 900,0 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 6 Copyright by CPqD©- 2000 ISDB 3/4 1/16 4K INT4 Multipath - single static echo tG =Gráfico 74 µs 3.1.3.4: Relação entre o atraso e a relação eco-sinal para taxa de erro de limiar ATSC 5 ATSC - Chip S 0 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 -10 ISDB - Chip J -15 -20 -25 -160 -120 -80 -40 0 Atraso (em us) 40 80 120 160 Echo delay (µs) Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 7 Copyright by CPqD©- 2000 E/C (dB) -5 C/N degradation with single echo •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 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 8 Copyright by CPqD©- 2000 C/N (dB) tG = 18,7 µs BER x C/N performance Better - Worse COFDM: robustness x payload Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 9 Copyright by CPqD©- 2000 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 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 10 Copyright by CPqD©- 2000 – Mobility - Doppler frequency shift - some trajects in São Paulo, near the transmitter 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) Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 – 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 11 Copyright by CPqD©- 2000 • TX station 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 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 Measurement period: Nov 9, 1999 to Abril 28, 2000 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 12 Copyright by CPqD©- 2000 • • • • • • • • 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 Power N = Noise power in channel bandwidth C/N = Signal to noise ratio Measured points 13 Copyright by CPqD©- 2000 •17 radials 15o apart •distances: 3, 6, 9, 12, 15, 20, 25, 30, 40 Km Field Tests - Coverage 127 test points: ATSC and DVB-T 2K III.3.1.4.7 Percentual de Recepção - Gráfico por Distância Critério: Margem > 0 Criterion: Margin > 0 dB 100% 80% 70% 60% 50% 40% 30% 20% 10% 0% 3 6 9 12 15 20 Distância (km) Distance (Km) ATSC DVB - 8k DVB - 2k 25 30 40 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 ISDB - 4k 14 Copyright by CPqD©- 2000 Percentual de Sites Percentage of sites 90% Field Tests - Coverage 127 test points: ATSC and DVB-T 2K III.3.1.4.8 Percentual de Recepção - Função Cumulativa Crtério: Margem > 0 Criterion: Margin > 0 dB 90% 80% 70% 60% 0 5 10 15 20 25 30 35 40 Distância (km) Distance (Km) ATSC DVB - 2k DVB - 8k ISDB - 4k Canal VHF-Alto/Analog. 3 a 5 Canal VHF-Alto/Analog. 2 a 5 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 15 Copyright by CPqD©- 2000 Percentage Percentual de Site of sites 100% Field Tests - Coverage 27 test points: ATSC, DVB-T 2K, III.3.1.5.7 Percentual de Recepção - Gráfico por Distância - 27 Pontos Simutâneos Critério: Margem > 0 Criterion: Margin > 0 dB 100% 80% 70% 60% 50% 40% 30% 20% 10% 0% 3 6 9 12 15 20 25 30 Distância (km) Distance (Km) 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 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 16 Copyright by CPqD©- 2000 Percentage Percentual de Site of sites 90% Field Tests - Coverage III.3.1.5.8 Percentual de Recepção - Função Cumulativa - 27 Pontos Simutâneos Critério: Margem > 0 Criterion: Margin > 0 dB 90% 80% 70% 60% 50% 40% 30% 0 5 10 15 20 25 30 Distância (km) Distance (Km) 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 Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 17 Copyright by CPqD©- 2000 Percentage of sites Percentual de Sites 100% Gap filler measurement sites GAP FILLER LOCALIZAÇÃO DOS PONTOS DE MEDIDAS 500m 1000m 1500m 2000m 2500m 3000m 24 2500m 2000m 21 20 32 22 33 1500m 34 35 13 11 12 13 5 6 17 18 19 1000m 43 8 9 10 500m 44 1 2 3 4 1000m 45 14 15 16 1500m 46 31 36 37 38 39 26 40 27 41 2000m 2500m 3000m 30 29 3500m Source: SET/ABERT Final Report - Part 2 Actuation Public Consultation 237 - June 02, 2000 PONTOS DE SOBREPOSIÇÃO DE SINAIS DA ESTAÇÃO PRINCIPAL E O GAP FILLER Superposition PONTOS FORA DA AREA DE ATUAÇÃO DO GAP FILLER Out of range PONTOS DE ATUAÇÃO DO GAP FILLER 18 Copyright by CPqD©- 2000 •Gap filler Radiation pattern •Tilted beam Outdoor Reception - Gap Filler Improvement of reception with gap filler Antenna is re-oriented with gap filler on/off Distance from main transmitter ~5,6 Km -> ~19 µs Actuation region 100% 100% Superposition region 100% 100% 90% 85% 77% 80% 77% 91% 90% 82% 82% 80% 73% 70% 60% 60% 50% 50% 40% 40% 30% 30% 23% 20% 20% 10% 10% 0% 0% OFF ATSC DVB-8K ISDB-8K 45% 27% ON OFF Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 ON ATSC DVB-8K ISDB-8K 19 Copyright by CPqD©- 2000 70% Indoor Reception 12 sites where the 3 systems were tested under identical conditions Normal Blender On People walking around near antenna Source: SET/ABERT Final Report - Part 2 Public Consultation 237 - June 02, 2000 20 Copyright by CPqD©- 2000 Percentage of good reception Indoor antenna: UHF log-periodic - Silver Sensor 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. 21 Copyright by CPqD©- 2000 Thank you for your attention