L64704 LSI Logic Corporation, L64704 Datasheet - Page 147

• Manufacturer Part Number: L64704
• Description: Satellite Decoder Technical Manual 5/97
• Manufacturer: LSI Logic Corporation

7.1.2
Code
Performance
Figure 7.2
Code Performance for
Viterbi Decoder
1.0e-02
1.0e-03
1.0e-04
1.0e-05
1.0e-06
7.1.3
Punctured
Codes
BER
2
X
The code performance for the Viterbi decoder is based on a simulation
of a numerically accurate model of the architecture.
results for a constraint length (K) of seven and code rates of 1/2, 3/4 and
7/8 that were seen on a small sampling of Satellite Decoder Evaluation
boards. Your results may be different.
The L64704 supports not only the basic rate equal to 1/2 decoding oper-
ations, but also code rates equal to 2/3, 3/4, 5/6 and 7/8. The code rate
and underlying depuncture scheme chosen dictates the proper sequence
of symbols on the DEM_I and DEM_Q inputs.
ture patterns for various code rates.
Viterbi Decoder Module
Bit error rate of 8-level quantized 64-state convolutional code
X
3
X
X
4
Eb/No (dB)
*
X
*
X
5
*
Table 7.1
Figure 7.2
*
6
78_8_96.dat
56_8_96.dat
34_8_96.dat
23_8_96.dat
12_8_96.dat
shows the punc-
*
shows the
*
X
7
7-3