Viterbi Convolutional Decoding; Viterbi ½; Viterbi ¼ - Safran CORTEX Series User Manual

1.6.1.6

Viterbi Convolutional Decoding

(notes 1)
1.6.1.6.1 Viterbi ½
Convolutional decoding and error-correction comply to CCSDS recommendations 101.0-B-3 (Blue
Book, 05/1992).
Code rate
Constraint length
Code generators
Phase relationship
Decoding mode
Puncturing
Parallel processing
Maximum (encoded) bit rate
Decoder status
1.6.1.6.2 Viterbi ¼
Application example: ERS-2 low bit rate satellite.
Code rate
Constraint length
Code generators
Maximum (encoded) bit rate
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HIGH DATA RATE RECEIVER
HDR-4G+ USER'S MANUAL
0.5 information bit per encoded bit
7 bits
G1 = 1111001; G2 = 1011011
Programmable association of G1 or G2 with first symbol:
Programmable inversion on output path of G2:
G1 - G2 Inverted (CCSDS) (G1 is associated with first symbol)
G1 - G2
G2 Inverted - G1 (G2 is associated with first symbol)
G2 – G1
Single decoder or separate decoders on I & Q (dual mode)
2 3 4 5 6 7
/ / / / / / or programmable in the registry.
3 4 5 6 7 8
1 to 16 parallel rate ½ Viterbi decoders on each I & Q with symbol
sequence compliant with NASA Space Network User's Guide (450-
SNUG)
In single Viterbi mode: up to 240 Mbps or 1160 Mbps with the high
rate menus
In dual Viterbi mode: up to 480 Mbps or 1160 Mbps with the high
rate menus (for Viterbi ½. else puncturing rate dependent).
In parallel processing mode (> 4xI / 4xQ): > 600 Mbps
Locked/unlocked. Symbol error rate (obtained by comparing the
input data to the re-encoded decoded data).
0.25 information bit per encoded bit
4 bits
G1 = 1000; G2 = 1100; G3 = 1010; G4 = 1001
240 Mbps
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Ref. DTU 100782
Is.Rev 3.5
Date: June 1, 2021
Safran Data Systems
.
Page 48