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looking for help on sofe demodulate and soft-input Viterbi decode

Started by minnows October 23, 2008
is there any article or paper that describe the detail algorithm of soft
demodulate and soft-input viterbi decode? Thank you!
minnows <minnows@tom.com> wrote:

>is there any article or paper that describe the detail algorithm of soft >demodulate and soft-input viterbi decode? Thank you!
Viterbi, A. J., "Error Bounds for convolutional codes and an asymptotically optimum decoding algorithm", _Trans. Inf. Theory_, 13, 260-269 (1967). Forney, G. D., "The Viterbi Algorithm", _Proc. IEEE_, v. 61, pp 268-278 (Mar 1973). Steve

minnows wrote:

> is there any article or paper that describe the detail algorithm of soft > demodulate and soft-input viterbi decode? Thank you!
For Viterbi algorithm, this is dead simple. Just calculate the path costs as the Eucleadian distances instead of the Hamming weights. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
On Thu, 23 Oct 2008 06:26:46 +0000 (UTC), spope33@speedymail.org
(Steve Pope) wrote:

>minnows <minnows@tom.com> wrote: > >>is there any article or paper that describe the detail algorithm of soft >>demodulate and soft-input viterbi decode? Thank you! > >Viterbi, A. J., "Error Bounds for convolutional codes and >an asymptotically optimum decoding algorithm", _Trans. Inf. >Theory_, 13, 260-269 (1967). > >Forney, G. D., "The Viterbi Algorithm", _Proc. IEEE_, v. 61, >pp 268-278 (Mar 1973). > >Steve
Those are probably the two best references, and the second might be preferrable if you just want to know how things work. Over the years Qualcomm, TI, and ADI have all put out some app notes written specifically for implementers that had very good descriptions of the algorithm and implementation issues. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
Eric Jacobsen  <eric.jacobsen@delete.ieee.org> wrote:

>(Steve Pope) wrote:
>>Viterbi, A. J., "Error Bounds for convolutional codes and >>an asymptotically optimum decoding algorithm", _Trans. Inf. >>Theory_, 13, 260-269 (1967).
>>Forney, G. D., "The Viterbi Algorithm", _Proc. IEEE_, v. 61, >>pp 268-278 (Mar 1973).
>Those are probably the two best references, and the second might be >preferrable if you just want to know how things work.
>Over the years Qualcomm, TI, and ADI have all put out some app notes >written specifically for implementers that had very good descriptions >of the algorithm and implementation issues.
Another paper I like is Andy Viterbi's paper on the GVA (generalized Viterbi algorithm) but I could not locate the reference to it. Also I think it's instructive to understand the algorithm in the probability domain, using measures instead of metrics, and relating that to the more usual formulation employing log-likelyhood ratios. There's a discussion of that in Heegard and Wicker, _Turbo Codes_. Finally one should probably understand the BCJR algorithm, and how it relates to the VA and GVA. Then you have the full picture. Steve