[op25-dev] rs decoder in hdu.cc

Matt D md123 at nycap.rr.com
Mon Jul 15 12:52:49 UTC 2013


> All of the error correcting block codes used in P25 are the sort where
> the codeword includes the encoded data verbatim; the code appends bits
> used for error correction, but a receiver can ignore those and just pull
> out the data bits.  This greatly increases the likelihood of
> post-decoding bit errors, but it works fine when the SNR is good.
> 
OK great, so I'll work on the error correction later.
My question now is how are the data bits currently extracted, or
separated, from the extra parity bits?  So, from the bit_vector&
frame_body I can extract the 240 bits the LCW information is in; the
question is how do I know where the 12, 6-bit symbols (hex bits or
codewords) are within this 240 bits?
Please excuse me if there is some obvious answer to this, I am asking in
interest of time.
Thanks!

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