ccsds 131.0-b-2

CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODINGS1R‐S ENCODER#1S2IN•••OUTR‐SENCODER#IFigure 4-2: Functional Representation of R-S InterleavingData bits to be encoded into a single Reed-Solomon Codeblock enter at the port labeled ‘IN’.Switches S1 and S2 are synchronized together and advance from encoder to encoder in thesequence 1,2, . . ., I, 1,2, . . ., I, . . ., spending one R-S symbol time (8 bits) in each position.One codeblock will be formed from kI R-S symbols entering ‘IN’. In this functionalrepresentation, a space of 2EI R-S symbols in duration is required between each entering setof kI R-S information symbols.Because of the action of S1, each encoder accepts k of these symbols, with each symbolspaced I symbols apart (in the original stream). These k symbols are passed directly to theoutput of each encoder. The synchronized action of S2 reassembles the symbols at the portlabeled ‘OUT’ in the same way as they entered at ‘IN’.Following this, each encoder outputs its 2E check symbols, one symbol at a time, as it issampled in sequence by S2.If, for I=5, the original symbol stream isd 1 1 . . . d5 1 d1 2 . . . d5 2 . . . d1 k . . . d5 k[2E × 5 spaces]then the output is the same sequence with the [2E × 5 spaces] filled by the [2E× 5] checksymbols as shown below:wherep 1 1 . . . p5 1 . . . p1 2E . . . p5 2Eid1 d i2 . . . d iK pi 1 . . . pi 2Eis the R-S codeword produced by the ith encoder. If q virtual fill symbols are used in eachcodeword, then replace k by (k – q) in the above discussion.CCSDS 131.0-B-2 Page 4-7 August 2011