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Unformatted text preview: ) ↓ 001001011101010111000000110011101000100110010000111101101100100101000110000110111111011110011100 ↑ LAST TRANSMITTED BIT (Bit 95) Figure 8-3: ASM Bit Pattern for Rate 1/3 Turbo Coded Data FIRST TRANSMITTED BIT (Bit 0) ↓ 0000001101000111011101101100011100100111001010001001010110110000 1111110010111000100010010011100011011000110101110110101001001111 ↑ LAST TRANSMITTED BIT (Bit 127) Figure 8-4: ASM Bit Pattern for Rate 1/4 Turbo Coded Data CCSDS 131.0-B-2 Page 8-3 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING FIRST TRANSMITTED BIT (Bit 0) ↓ 001001011101010111000000110011101000100110010000111101101100100101000110000110111111011110011100 110110100010101000111111001100010111011001101111000010010011011010111001111001000000100001100011 ↑ LAST TRANSMITTED BIT (Bit 191) Figure 8-5: ASM Bit Pattern for Rate 1/6 Turbo Coded Data 8.4 LOCATION OF ASM 8.4.1 The ASM shall be attached to (i.e., shall immediately precede) the codeblock (if Reed-Solomon encoded), the codeword (if Turbo or LDPC encoded), or the transfer frame (if convolutionally encoded only or uncoded). 8.4.2 The ASM shall immediately follow the end of the preceding codeblock (if ReedSolomon encoded), the codeword (if Turbo or LDPC encoded), or the transfer frame (if convolutionally encoded only or uncoded); i.e., there shall be no intervening bits (data or fill) preceding the ASM. 8.5 RELATIONSHIP OF ASM TO REED-SOLOMON, TURBO, AND LDPC CODEBLOCKS AND CODEWORDS 8.5.1 The ASM shall NOT be a part of the encoded data space of the Reed-Solomon Codeblock, and it shall not be presented to the input of the Reed-Solomon encoder or decoder. NOTE – This prevents the encoder from routinely regenerating a second, identical marker in the check symbol field under certain repeating data-dependent conditions (e.g., a test pattern of 01010101010 ... among others), which could cause synchronization difficulties at the receiving end. The relationship among the ASM, Reed-Solomon Codeblock, and Transfer Frame is illustrated in figure 4-1. 8.5.2 Similarly, the ASM shall n...
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This document was uploaded on 03/06/2014.

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