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3.4.3.3. Encoding
The Telemetry Simulator provides the capabilities of scrambling and convolutional, Reed-Solomon, Turbo
encoding and LDPC encoding. These capabilities are provided to test the corresponding decoding functionalities
in the downlink Telemetry Units, which are license dependent.
In Low, Intermediate and High Bandwidth modes, these scrambling and encoding capabilities are available in
File, Pseudo and BERT File operating modes.
3.4.3.3.1. Convolutional Encoding
This processing provides the capabilities corresponding to the rates ½, 1/3, 2/3, 3/4, 5/6, 7/8 constraint length 7
Viterbi encoding recommended in § 3 of CCSDS 131.0-B-3.The corresponding decoding is license dependent.
The real-time Convolutional encoding is available only with an Intermediate and High Bandwidth Telemetry
Simulator. When using a Low Bandwidth Telemetry Simulator in Lan or Replay mode, the encoding must be pre-
calculated in the data.
The availability of the Convolutional encoding depends upon the fact that the TMS operates in Low Bandwidth
mode or in Intermediate/High Bandwidth mode.
It is activated by programming the parameter Data Encoding to the desired combination of Viterbi, Viterbi
Inverted and Scrambling.
3.4.3.3.2. Tcm
This processing provides the capabilities corresponding to the rates 2.00/3, 2.25/3, 2.50/3, 2.75/3 Tcm encoding
recommended
in
Tcm decoding and encoding is only available in High Bandwidth.
3.4.3.3.3. Reed-Solomon
This processing provides the capabilities corresponding to the encoding recommended in § 4 of CCSDS 131.0-
B-3, including virtual filling and interleaving. The corresponding decoding is license dependent.
The Reed-Solomon encoding is available in the File, Pseudo and BERT File operating modes.
It is activated by programming the parameter Frame Encoding to Reed-Solomon. For SPS version E4R32 and
higher, the Reed-Solomon encoding is selectable as base Beta or Alpha (default is Beta for previous versions).
For SPS version E6R23 it is possible to choose the coded to decoded ratio. The frames are generated by using
the parameters Sync. Word, Sync. Word Length and Frame Length of the TMU associated owing to the
parameter TM Flow for BER/Encoding. The interleaving depth and the need of virtual filling are automatically
deduced from the TMU Frame Length.
In Pseudo mode, the encoded frame length is the Frame Length of the associated TMU. It corresponds to the
length of (sync. Marker + codeblock), which has to be configured for TMU frame synchronization too. In File
mode, the uncoded data have to be placed at their location in the emitted codeblock, hence, after the bytes
corresponding to the Attached Sync. Marker. Moreover, it is possible to repeat the encoding of several
consecutive frames. In this case, the TMS Format Length has to match the several frames which have to be
encoded, and so to be configured to the value corresponding to the TMU Frame Length times the number of
encoded frames. In this case the data shall be organized in the file according to the following structure:
© Safran Data Systems
COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
LBW mode: available only in File, Pseudo and BERT File operating modes. (all rates)
IBW/HBW mode: available all operating modes (only 1/2 rate)
CCSDS
413.0-G-2.
This document is the property of
It cannot be duplicated or distributed without expressed written consent.
The
corresponding
Safran Data Systems
.
Ref.
DTU 100042
Is.Rev.
5.17
Date:
Dec.
03, 2021Sept. 30, 2021
decoding
is
license
dependent.
Page 123
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