COMMAND RANGING & TELEMETRY UNIT CORTEX
CRT QUANTUM USER'S MANUAL
Ref. DTU 100042
Is.Rev. 5.17
Date: Dec.
03, 2021Sept. 30, 2021
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It cannot be duplicated or distributed without expressed written consent.
LDPC Encoding 1.1.1.1.1
This processing provides the capabilities corresponding to the encoding recommended in § 5 of CCSDS 131.0-
B-3. The corresponding decoding is license dependent.
The LDPC-encoding is available in the File, Pseudo and BERT File operating modes.
It is activated by programming the parameter Frame Encoding to LDPC-code. The frames are generated by
using the parameters Frame Length and LDPC Code Rate of the TMU associated owing to the parameter TM
Flow for BER/Encoding. In the particular case of LDPC decoding, the TMU Frame Length has to be configured
with the uncoded information block length, expressed in bits. The Sync. Marker is automatically deduced from
the TMU LDPC Code Rate.
Code Block Length
bits [bytes]
Table 25: LDPC code : information block and codeblock lengths
In Pseudo mode, the Frame Length of the associated TMU must be configured with the information block length
expressed in bits. The length of (sync. Marker + LDPC code block) is given by the formula:
where is the code rate and the information block length in bits.
In File mode, the information data blocks (and only them) have to be provided in the selected file. Moreover, it is
possible to repeat the encoding of several consecutive blocks. 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 blocks (Hence, in this case, the TMS format length is
expressed in bits too). In this case the data shall be organized in the file according to the following structure:
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