3 s1 is in the position shown 1 for the first symbol

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1, POSITION 2. 3. S1 IS IN THE POSITION SHOWN (1) FOR THE FIRST SYMBOL ASSOCIATED WITH AN INCOMING BIT. 4. 5. = MODULO-2 ADDER. = INVERTER. Figure 3-1: Basic Convolutional Encoder Block Diagram CCSDS 131.0-B-2 Page 3-3 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING 3.4 PUNCTURED CONVOLUTIONAL CODES 3.4.1 The punctured convolutional code shall have the following characteristics: (1) Nomenclature: Punctured convolutional code with maximum-likelihood decoding. (2) Code rate (r): 1/2, punctured to 2/3, 3/4, 5/6 or 7/8. (3) Constraint length (K): 7 bits. (4) Connection vectors: G1 = 1111001 (171 octal); G2 = 1011011 (133 octal). (5) Symbol inversion: None. 3.4.2 The puncturing patterns for each of the punctured convolutional code rates shall be as specified in table 3-1. NOTE – Figure 3-2 depicts the punctured encoding scheme. G1 INPUT D D D D C1 D OUTPUT PUNCTURE (table 3-1) D C2 G2 Figure 3-2: Punctured Encoder Block Diagram Table 3-1: Puncture Code Patterns for Convolutional Code Rates Puncturing Pattern 1 = transmitted symbol 0 = non-transmitted symbol C1: 1 0 C2: 1 1 Output Sequence Code Rate C1(t), C2(t) denote values at bit time t 2/3 C1(1) C2(1) C2(2) ... C1: 1 0 1 C2: 1 1 0 3/4 C1(1) C2(1) C2(2) C1(3) ... C1: 1 0 1 0 1 C2: 1 1 0 1 0 5/6 C1(1) C2(1) C2(2) C1(3) C2(4) C1(5) ... C1: 1 0 0 0 1 0 1 C2: 1 1 1 1 0 1 0 7/8 C1(1) C2(1) C2(2) C2(3) C2(4) C1(5) C2(6) C1(7) ... CCSDS 131.0-B-2 Page 3-4 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING 4 REED-SOLOMON CODING 4.1 OVERVIEW The Reed-Solomon (R-S) codes defined in this section are powerful burst error correcting codes. One of two different error-correcting options may be chosen. For maximum performance (at the expense of accompanying overhead) the E=16 option can correct 16 R-S symbols in error per codeword. For lower overhead (with reduced performance) the E=8 option can correct 8 R-S symbols per codeword. The Reed-Solomon code may be used alone...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online