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Unformatted text preview: , and as such it provides an excellent forward error correction capability in a burst-noise
channel. However, should the Reed-Solomon code alone not provide sufficient coding gain,
it may be concatenated with the convolutional code defined in section 3. Used this way, the
Reed-Solomon code is the outer code, while the convolutional code is the inner code.
DATA RANDOMIZATION The pseudo-randomizer defined in section 9 shall be used unless the system designer verifies
that the concerns identified in the note below are resolved by other means.
NOTE – The recommended Reed-Solomon codes, by themselves, cannot guarantee
sufficient bit transitions to keep receiver symbol synchronizers in lock. Because
of the quasi-cyclic nature of these codes, undetected decoding errors may result
from incorrect codeblock synchronization. The pseudo-randomizer is also used
to aid signal acquisition and to mitigate spectral lines in the transmitted signal.
4.2.2 FRAME VALIDATION The Frame Error Control Field (FECF) specified in references  and  is optional. The
system designer may choose to use it for additional codeblock validation, particularly with
the E=8 code.
NOTE – The Reed-Solomon code with E=16 has an extremely low undetected error rate,
and that with E=8 has an undetected error rate low enough for some applications.
Therefore the R-S decoder may be used alone to validate the codeblock, and
consequently the contained TM Transfer Frame (reference ) or AOS Transfer
Frame (reference ).
PARAMETERS The parameters of the selected Reed-Solomon (R-S) code are as follows: CCSDS 131.0-B-2 Page 4-1 August 2011 CCSDS RECOMMENDED STANDARD FOR TM SYNCHRONIZATION AND CHANNEL CODING a) J shall be 8 bits per R-S symbol.
b) E shall be 16 or 8 R-S symbols.
NOTE – E is the Reed-Solomon error correction capability, in symbols, within a R-S
4.3.2 GENERAL CHARACTERISTICS The code shall conform to the following general characteristics:
a) J, E, and I (the depth of interleaving) are independent parameters.
b) n = 2J–1 = 255 symbols per R-S codewor...
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- Spring '14