Crc Frame Checking; (255,223) Reed-Solomon Decoding - Safran CORTEX Series User Manual

3.4.5

CRC Frame Checking

Reconstructed frames will be verified only if parameter Frame Checking is set to CRC.
The CRC is user-programmable via two parameters: CRC Polynomial (CRC16, CCITT, etc...) and
CRC Preset Value (usually all bits set to 0 or to 1).
The CRC value is supposed to be the last two bytes of each frame. The CRC Preset Value is added to
the computed checksum.
3.4.6

(255,223) Reed-Solomon Decoding

Reed-Solomon coding technique is well suited for burst error correction. It can be used in conjunction
with convolutional encoding to allow data reconstruction with the lowest error probability. Reed-
Solomon decoding and error-correction by the CORTEX HDR complies to the CCSDS recommendation
101.0-B-3 (Blue Book - May 1992). The following coding characteristics should be used:
 J = 8 bits per R-S symbol
 Conventional and dual basis supported
 E = 16 R-S symbol error correction capability within a R-S codeword (coded to decoded
information ratio = 255/223),
 Interleaving depth: auto-adjusted from 1 to 8 (frame-length dependent),
 Virtual filling for shorten RS code
 Other characteristics: see CCSDS recommendation 101.0-B-3.
The Virtual fill length and Interleaving depth are automatically deduced by the HDR from the CADU
length set by the operator with the following formula:
For I = 1:
For 1 < I ≤ 8:
V max = 15
CL max = 2044
CL min = 244
I: Interleaving depth
CL: CADU length (in bytes)
V: Virtual fill length (in bytes)
Vmax: Virtual fill length max (in bytes)
The R-S decoder status includes two counters (good frames and bad frames), the number of corrected
errors (per frame) and the BER.
© Safran Data Systems – IMP000074 e14r1
HIGH DATA RATE RECEIVER
HDR-4G+ USER'S MANUAL
240 + 4 ≤ CL = (255-V) + 4
CL = (255-V) x I + 4
240 x I + 4 <
Ref.
Is.Rev
Date:
≤ 255 + 4
≤
Safran Data Systems
This document is the property of
It cannot be duplicated or distributed without expressed written consent.
DTU 100782
3.5
June 1, 2021
255 x I + 4
.
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