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Digital Television Broadcasting SystemsTesting in Brazil
Kiev, Ukraine - 13-15 November 2000Interregional Seminar on the Transition from SECAM to Digital TV
Broadcasting
Renato Maroja - [email protected]ção 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 (µs)
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(d
B)
Digital signal + gated Noise ⇒ C/NeqGate: 30s cycle, 12,5 Hz to 100 Hz, fixed TWBER < 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
(d
B)
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 (µs)
tG = 74 µs
Source: SET/ABERT Final Report - Part 2Public Consultation 237 - June 02, 2000
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C/N degradation with single echo
C/N
(dB
)•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 µs
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 Thresholdor 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)
Per
cent
ual d
e S
ites
ATSC DVB - 8k DVB - 2k ISDB - 4k
Distance (Km)
Per
cent
age
of s
ites
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)
Per
cen
tual
de
Site
ATSC DVB - 2k DVB - 8k ISDB - 4k Canal VHF-Alto/Analog. 3 a 5 Canal VHF-Alto/Analog. 2 a 5
Distance (Km)
Per
cent
age
of s
ites
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)
Per
cen
tual
de
Site
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
cent
age
of s
ites
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)
Per
cent
ual d
e S
ites
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
cent
age
of s
ites
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 µs
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
cent
age
of g
ood
rece
ptio
n12 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