Digital Television Broadcasting Systems
Testing in Brazil
Renato Maroja - maroja@cpqd.com.br
Fundação CPqD - www.cpqd.com.br
Campinas - SP - Brazil
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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
•
•
•
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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
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• 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
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• 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
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– 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
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(*) 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
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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
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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
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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
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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
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– 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
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• 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
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•
•
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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 Power
N = Noise power in channel bandwidth
C/N = Signal to noise ratio
Measured points
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•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
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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
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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
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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
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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
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•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
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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
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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.
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Thank you for your attention