431 the encoder shall accept as input a telemetry

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Unformatted text preview: 419 459 468 209 311 211 510 320 0 285 554 809 185 49 101 82 898 627 154 65 81 823 50 413 462 175 715 537 722 37 488 179 430 264 0 1189 458 460 1039 1000 1265 1223 874 1292 1491 631 464 461 844 392 922 256 1986 19 266 471 1166 1300 1033 1606 ENCODING 7.4.3.1 The encoder shall accept as input a Telemetry Transfer Frame of length k as per table 7-5. 7.4.3.2 Codewords consistent with the parity-check matrices in 7.4.2 shall be produced by performing matrix multiplication by block-circulant generator matrices. NOTE – This family of codes supports rates K/(K+2), where K=2 for a rate 1/2 code, K=4 for rate 2/3, and K=8 for rate 4/5. Corresponding generator matrices, G, have size MK × M(K + 3) if punctured columns are described in the encoding, or MK × M(K + 2) if punctured columns are omitted. CCSDS 131.0-B-2 Page 7-10 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING Table 7-5: Codeword Lengths for Supported Code Rates (Measured in Bits) Codeword length n Telemetry Transfer Frame Length or Information block length k rate 2/3 rate 4/5 1024 2048 1536 1280 4096 8192 6144 5120 16384 7.4.3.3 rate 1/2 32768 24576 20480 The generator matrices shall be constructed as follows: 1) P shall be the 3M × 3M submatrix of H consisting of the last 3M columns. Q shall be the 3M × MK submatrix of H consisting of the first MK columns. 2) W = ( P −1Q)T shall be computed, where the arithmetic is performed modulo-2. 7.4.3.4 The matrix G = [ I MK W ] shall be constructed, where IMK is the MK × MK identity matrix, and W is a dense matrix of circulants of size MK × 3M. 7.4.3.5 The last M columns of G shall be punctured. CCSDS 131.0-B-2 Page 7-11 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING 8 FRAME SYNCHRONIZATION 8.1 8.1.1 OVERVIEW SYNCHRONIZATION Frame or Codeblock synchronization is necessary for proper decoding of Reed-Solomon, Turbo, and LDPC Codewords, and subsequent processing of the Transfer Frames. Furthermore, it is necessary for synchronization o...
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This document was uploaded on 03/06/2014.

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