Digital Signal Processing Reference
In-Depth Information
The net data rate additionally depends on the code rate of the convolu-
tional coding used and on the Reed Solomon error protection RS(188, 204)
as follows:
net_data_rate = gross_data_rate • 188/204 • code_rate;
Since the factor of 4 cancels out, the overall formula for determining the
net data rate of DVB-T signals is independent of the mode (2K or 8K) and
is:
net_data_rate = 188/204 • code_rate • log
2
(m) • 1(1 + guard)
• channel • const1;
where
m = 4 (QPSK), 16 (16-QAM), 64 (64-QAM);
log
2
(m) = 2 (QPSK), 4 (16-QAM), 6 (64-QAM);
code rate = 1/2, 2/3, 3/4, 5/6, 7/8;
guard = 1/4, 1/8, 1/16, 1/32;
channel = 1 (8MHz), 7/8 (7MHz), 6/8 (6 MHz);
const1 = 6.75 • 10
6
bits/s;
Table 20.11.
Net data rates with non-hierarchical modulation in the 8 MHz
DVB-T channel
Modulation
Code rate
Guard 1/4
Guard 1/8
Guard 1/16
Guard 1/32
Mbit/s
Mbit/s
Mbit/s
Mbit/s
QPSK
1/2
4.976471
5.529412
5.854671
6.032086
2/3
6.635294
7.372549
7.806228
8.042781
3/4
7.464706
8.294118
8.782007
9.048128
5/6
8.294118
9.215686
9.757785
10.05348
7/8
8.708824
9.676471
10.24567
10.55617
16QAM
1/2
9.952941
11.05882
11.70934
12.06417
2/3
13.27059
14.74510
15.61246
16.08556
3/4
14.92941
16.58824
17.56401
18.09626
5/6
16.58824
18.43137
19.51557
20.10695
7/8
17.41765
19.35294
20.49135
21.11230
64QAM
1/2
14.92941
16.58824
17.56401
18.0926
2/3
19.90588
22.11765
23.41869
24.12834
3/4
22.39412
24.88235
26.34602
27.14439
5/6
24.88235
27.64706
29.27336
30.16043
7/8
26.12647
29.02941
30.73702
31.66845
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