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Unformatted text preview: Frames, if
the Physical Channel is not Reed-Solomon, Turbo, or LDPC coded) shall be synchronized by
using a stream of fixed-length Codeblocks or Codewords (or Transfer Frames) with an
Attached Sync Marker (ASM) between them. NOTE – Synchronization is acquired on the receiving end by recognizing the specific bit
pattern of the ASM in the Physical Channel data stream; synchronization is then
verified by making further checks.
188.8.131.52 If convolutional code is used, the ASM shall be convolutionally encoded. 184.108.40.206 If an inner convolutional code is used in conjunction with an outer Reed-Solomon
code, the ASM shall be encoded by the inner code but not by the outer code. (See section 3.)
8.3 ASM BIT PATTERNS 8.3.1 The ASM for data that is not Turbo or LDPC coded shall consist of a 32-bit (4-octet)
marker with a pattern shown in figure 8-1.
8.3.2 The ASM for data that is Turbo coded with nominal code rate r = 1/2, 1/3, 1/4, or 1/6
shall consist of a 32/r-bit (4/r-octet) marker with bit patterns shown in figures 8-2 through 8-5.
8.3.3 The ASM for data that is LDPC coded with nominal code rate r = 7/8 shall consist of
a 32-bit marker with bit pattern shown in figure 8-1.
8.3.4 The ASM for data that is LDPC coded with code rate r = 1/2, 2/3, or 4/5 shall consist
of a 64-bit marker with bit pattern shown in figure 8-2. NOTE – The ASM bit patterns are represented in hexadecimal notation as:
ASM for uncoded data, convolutional,
Reed-Solomon, concatenated, and rate7/8 LDPC coded data:
ASM for rate-1/2 Turbo and rates 1/2, 2/3,
and 4/5 LDPC coded data:
ASM for rate-1/3 Turbo coded data:
ASM for rate-1/4 Turbo coded data:
ASM for rate-1/6 Turbo coded data: CCSDS 131.0-B-2 1ACFFC1D
25D5C0CE8990F6C9461BF79C DA2A3F31766F0936B9E40863 Page 8-2 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING FIRST TRANSMITTED BIT
0001 1010 1100 1111 1111 1100 0001 1101
↑ LAST TRANSMITTED BIT
(Bit 31) Figure 8-1: ASM Bit Pattern for Uncoded, Convolutional, Reed-Solomon,
Concatenated, and Rate 7/8 LDPC Coded Data FIRST TRANSMITTED BIT
LAST TRANSMITTED BIT
(Bit 63) Figure 8-2: ASM Bit Pattern for Rate 1/2 Turbo and Rates 1/2, 2/3, and 4/5 LDPC
Coded Data FIRST TRANSMITTED BIT
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This document was uploaded on 03/06/2014.
- Spring '14