CW software decoder algorithm?
 

Dear all

I am looking for ideas for a software CW decoder with ASCII output.
There are a number of programs published - what algorithms do these use in
general?
I presume the software would have to have some sort of PLL to select and
filter a signal
and then an adaptive algorithm to allow for sending operator error in
keying, noise and variations in keying speed. I am looking for a solution
which trades off accuracy for minimum codespace and speed. If necessary,
some of the work could be done in hardware - eg I could limit and square up
the audio waveform and present it the processor as digital level
transitions, so AGC would not be an issue.
Any ideas?

Thanks in advance

Richard