Re: fldigi CW decoding problems
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Thanks Bob,
Once upon a time I tried to get Fldigi to copy my hand sent morse. I eventually managed it. I've looked at the algorithm and indeed have coded into a keyer/decoder I built using an Arduino. The algorithm works fine with a pure digital on-off signal. However
trying to isolate the on-off signal from the audio pass-band was more problematic. The DSP requirements were beyond the capabilities of the Arduino.
Your comment on the effects of the filter are very relevant. When I use fldigi on-air as a back-up to head copy, it fails dramatically. Head copy requires a narrowish filter. Too narrow and the ringing even makes head copy difficult. Fldigi, as you said, needs
a wider filter.
73 Phil GM3ZZA
From: [email protected] <[email protected]> on behalf of Bob McGraw - K4TAX <rmcgraw@...>
Sent: 24 January 2025 7:13 PM To: [email protected] <[email protected]> Subject: Re: [winfldigi] fldigi CW decoding problems ?
A study of the on-line documentation for starters.?? Forget trying to decode hand sent elements.? Computer sent elements decode just fine.?? There is no anticipatory algorithm that tells FLDIGI what's coming next.?? Head copy is always
superior to computer copy.?? If you are expecting the computer to do the decoding for all CW signals, forget it, it won't happen.?? Good code equals good copy.? Poor sent code equal's poor copy.
Don't get the receiver bandwidth too narrow as filters can ring, thus contribute to poor copy.? I normally run 1.0 to 1.5 kHz receiver BW. I find FLDIGI to be one of the better CW decoding applications.? In fact I use it with N1MM as the CW engine.?? I have HRD, MixW4, CW Get, and a couple of other CW applications.?? Each has their merits.???? My Elecraft K3S does an excellent job decoding CW signals........if the parameters, threshold, etc. are correctly adjusted.? It takes patience and lots of trial and error, along with understanding of signal and band noise relationships.?? There is NO one setting that will make it always great. 73 Bob, K4TAX |
Philip Rose