Viterbi Convolutional Decoding; General - Safran CORTEX Series User Manual

3.3.3

Viterbi Convolutional Decoding

3.3.3.1

General

Convolutional coding technique is well suited for telemetry channels with predominant Gaussian noise.
Convolutional decoding and error-correction by the CORTEX HDR complies to the CCSDS
recommendation 101.0-B-3 (Blue Book - May 1992) and to the NASA Space Network User's Guide
(450-SNUG, June 2002):
 Viterbi decoding of the data received from the bit synchronizer.
 Viterbi de-puncturing if required.
 Operating mode: single or dual Viterbi mode.
 Processing mode: single decoder or parallel decoders (up to 16 decoders on each I & Q).
 BER estimate by re-encoding the Viterbi decoded data and comparing the re-encoded data to
the data fed to the Viterbi decoder. Note: if the Viterbi decoder(s) fails to lock (BER too high),
check the Viterbi characteristics (Normal or inverted G2, single or dual Viterbi, G1G2 or
G2G1 sequencing) and verify the setting of the I & Q output mode parameter (Demodulator
output to the Viterbi decoder(s) input).
Test & Monitoring: a number of status enable to monitor the Viterbi decoding process: decoder lock
status, BER (in %), etc...
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Ref. DTU 100782
Is.Rev 3.5
Date: June 1, 2021
Safran Data Systems
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