Viterbi decoder package released

[Phil Karn <karn@unix.ka9q.ampr.org>]

As promised, I have uploaded my Viterbi decoder package:

ftp://ftp.ucsd.edu/hamradio/packet/tcpip/incoming/viterbi.tar.gz
ftp://ftp.ucsd.edu/hamradio/packet/tcpip/incoming/viterbi.zip

This package implements a coder and soft decision Viterbi (maximum
likelihood) decoder for the rate 1/2 K=7 NASA standard convolutional
code. It includes a driver program for test purposes.

The decoder runs at about 45.5 kilobits/sec on a 66 MHz 486DX2 under
BSDI1.1 and gcc 1.42. (Interestingly enough, it runs only about 40.8
kb/s under gcc 2.5.8, even with full optimization).  This is about
6.6x slower than my Fano decoder on a "clean" channel. But unlike a
Fano decoder, which bogs down on a noisy channel, the Viterbi decoder
runs at a constant rate even when the signal is very weak (though not
without errors, of course).

Phil