COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
This document is the property of Safran Data Systems.
It cannot be duplicated or distributed without expressed written consent.
3.3.6. Data Decoding
The PCM bit stream from the Bit Synchronizer is processed in the following order (license-dependant) :
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.
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:
To Next Page
Loading...