Data Decoding; Descrambling - Safran CORTEX CRT Quantum User Manual

Data Decoding

3.3.6.
The PCM bit stream from the Bit Synchronizer is processed in the following order (license-dependant) :
Selection of the data decoding technique is by configuration commands addressed to the TMU.

3.3.6.1. Descrambling

Scrambling technique is used to maintain bit or symbol synchronization on the telemetry processing chain, by
always having a minimum bit transition density on the received telemetry signal. Scrambling is not required when
telemetry transmission uses certain modulation techniques (for example bi-phase PCM coding) or convolutional
codes.
Descrambling by the CORTEX CRT Quantum complies to the CCSDS recommendation CCSDS 131.0-B-3 The
pseudo-random sequence should be generated using the following polynomial:
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
 Bi-Phase, DM-M or DM-S decoding,
 Convolutional Viterbi decoding (one dual or single-input decoder or two separate
single-input decoders on I and Q channels): rate 1/2, 1/3, 2/3, 3/4, 5/6, 7/8
Or Tcm decoding: rate 2.00/3, 2.25/3, 2.50/3, 2.75/3.
 Differential QPSK decoding (DQPSK or DOQPSK, DSOQPSK),
 Differential decoding (NRZ-M or NRZ-S),
 R-NRZ decoding,
 Frame synchronization,
 Descrambling,
 Reed-Solomon decoding or Turbo decoding,
 Data time-tagging, storage and transmission to the Telemetry Clients.
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Safran Data Systems
.
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
Page 61