Morse decoder circuit8/15/2023 It appeared the simple OpAmp circuit “squaring” the received audio had difficulty if the received signal wasn’t literally many many dB above the noise. The signal received by the radio needed to be an extremely strong signal. ((showing my age)) The small GWBasic program could certainly decode it.īoth stations were sending at the same speed and were very strong. This was then applied to one of the printer port pins on my Tandy TRS-80 or my old 286-12Mhz. I once built a simple LM 741 OpAmp circuit that took the receiver’s speaker audio and converted or “squared” it. ((Not saying the PICAXE approach will not work.)) They really perform extremely well receiving really weak signals. There are many software freebies out there that are great! Especially with the advent of Sound Cards these days and Digital Signal Processing etc. RickHarris, stick with a PC software/sound card Morse Code decoder. Perhaps a daisy-chain of PICAXE's each doing its own thing the first timing dit or dah length, another looking for inter-character gaps, a third determining which are dits and dahs, another working out what that sequence means and passing it on to an AXE033 or another PICAXE driving an LCD.Ī PC or fast micro would have plenty of time to do all that in one program. It's tempting to say buffer the length of each dit or dah then post-process when an inter-character gap is received but then we're back to the issue of how much processing time there is between detecting that and the next dit or dah. Turning dits and dahs into a character could also be time intensive if done the wrong way, ie a lookup table checked after each dit or dah I'd use a binary tree, a sequence of IF-THEN's to determine what each could be, but that might be getting ahead of myself. Haven't tried it but it should be possible if the PICAXE is fast enough to do its thing between dit and dah gaps - The biggest problem is perhaps working out how long a dit or dah is to start with to be able to distinguish the two.
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