Hi team -
Perhaps someone who has experience with the Reed-Solomon decoder core can nudge me in the right direction?
I am using the reed_solomon 12.0 decoder core in DSP Builder/Simulink (2012a). The codeword we are trying to decode is a DOCSIS cable modem range request (RNG-REQ), which appears to be encoded using a RS(44,34) scheme [34 information bytes + 10 RS parity bytes = 44 byte RS codeword.
I understand most of the parameters for this Reed-Solomon decoder core and believe the correct parameters, as defined by the DOCSIS spec, are:
1. RS codeword of 8 bits/symbol
2. 44 RS symbols/codeword
3. 10 check symbols/codeword
4. field polynomial of 285
The parameters I am not sure about are the "5. first root of polynomial generator" (set to 0 currently) and the "6. root spacing in polynomial generator" (set to 1 currently). Can anyone shed a little light on how to explicitly determine these two values? I found the example in the RS Compiler User Guide to be a little lacking.
When I try to decode a captured codeword, the decoder asserts decfail which tells me 1) the core parameters are wrong for my codeword, or 2) the codeword I am trying to decode is bad or not assembled properly.
I know the rest of the model is operating correctly, since when I switch the decoder to the supplied "DVB Standard" and use a known-good RS(204,188) test vector the decoder behaves perfectly.
Anyway, thanks in advance for any help, suggestions, or appropriate voodoo! :)
Charles
Perhaps someone who has experience with the Reed-Solomon decoder core can nudge me in the right direction?
I am using the reed_solomon 12.0 decoder core in DSP Builder/Simulink (2012a). The codeword we are trying to decode is a DOCSIS cable modem range request (RNG-REQ), which appears to be encoded using a RS(44,34) scheme [34 information bytes + 10 RS parity bytes = 44 byte RS codeword.
I understand most of the parameters for this Reed-Solomon decoder core and believe the correct parameters, as defined by the DOCSIS spec, are:
1. RS codeword of 8 bits/symbol
2. 44 RS symbols/codeword
3. 10 check symbols/codeword
4. field polynomial of 285
The parameters I am not sure about are the "5. first root of polynomial generator" (set to 0 currently) and the "6. root spacing in polynomial generator" (set to 1 currently). Can anyone shed a little light on how to explicitly determine these two values? I found the example in the RS Compiler User Guide to be a little lacking.
When I try to decode a captured codeword, the decoder asserts decfail which tells me 1) the core parameters are wrong for my codeword, or 2) the codeword I am trying to decode is bad or not assembled properly.
I know the rest of the model is operating correctly, since when I switch the decoder to the supplied "DVB Standard" and use a known-good RS(204,188) test vector the decoder behaves perfectly.
Anyway, thanks in advance for any help, suggestions, or appropriate voodoo! :)
Charles