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Author Topic: CW decoder for SDR? for Linux, but better than fldigi  (Read 357 times)

N3KXZ

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CW decoder for SDR? for Linux, but better than fldigi
« on: November 29, 2022, 06:19:03 PM »

I have been attempting to use fldigi with my RTL-SDR dongle to decode CW transmissions (I don't know Morse Code). I don't feel fldigi is very good at it. Do any of you know a better software to use to decode CW on Linux?

Thanks,
Keith
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K6SDW

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #1 on: November 29, 2022, 06:54:45 PM »

Actually, FLdigi is the best I've found, and none are perfect....nothing beats the human brain when decoding CW. The ARRL/QST new technical editor KE0OG recently did a YouTube review on computer/software CW decoders and does an excellent job explaining why our brains will always be the best, hands down.

I rely on FLdigi when I'm trying to copy QRQ speed demons, particularly during contest time. Some good CW practice software out there for learning code and increasing your speed. And of course, the tried-and-true method just start listening on the air.

After many many years operating digital, I'm moving back to CW - my first ham radio mode starting back in 1965 with a Knightkit T60 xmtr and Lafayette general coverage rcvr with bandwith wider than a barn door.

GL/73
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N3KXZ

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #2 on: November 29, 2022, 08:30:11 PM »

Well... might there be certain settings which will help FLdigi work better at decoding CW? There are a lot of FLdigi settings which I don't yet understand how to use.
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K6SDW

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #3 on: November 29, 2022, 08:51:37 PM »

I agree, FLdigi is confusing so back to YouTube and I found a wizard or two that posted some good advice configuring the software. If you're interested in learning to copy CW (a dying art IMO) I really like the app from G4FON, excellent software....

Hope this helps....73
« Last Edit: November 29, 2022, 09:11:14 PM by K6SDW »
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G4AON

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #4 on: November 30, 2022, 01:44:25 AM »

nothing beats the human brain when decoding CW.
The fundamental "problem" is that Morse is a hand sent mode, intended to be received by ear, no computer can cope with the additional spaces and strange shortened "words", my CW Skimmer Server feeds the Reverse Beacon Network and sometimes sends false callsigns, such as K4AB when the caller actually sent their callsign as D <space> K4AB... Quite a difference.

If you want to use computer coding/decoding, Morse is not the mode to use, try VarAC for relatively low cost chatting on digital mode Vara. It works down to similar signal levels to FT8, but with the bonus of actually conversing with a human.

73 Dave
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G8FXC

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #5 on: November 30, 2022, 02:40:57 AM »

I have been attempting to use fldigi with my RTL-SDR dongle to decode CW transmissions (I don't know Morse Code). I don't feel fldigi is very good at it. Do any of you know a better software to use to decode CW on Linux?

Thanks,
Keith

While I'm not as black-and-white about Morse decoders as the real hard-core CW operators, I think you'll find that all of them are unsatisfactory if you have no code reading ability at all. As others have said, Morse was designed to be decoded by a trained human and it lacks the rigor of a modern digital mode. I can copy CW up to something around 20wpm for boilerplate exchanges but get into trouble as soon as the guy at the far end deviates from the standard "QTH London. Ant folded dipole. UR 599, 599, BTU..." So I usually have a decoder running as a safety net. Unless the code coming in was machine generated and the signal is strong with virtually no interference, the decoded text is going to contain a lot of errors, but it will usually be sufficient to fill in the blanks in my imperfect head-copy.

In terms of which decoder - I find that fldigi is as good as most. I run a Yaesu FTdx101D which has a built-in decoder and I often use that to avoid overloading my PC screen with windows. I've also built a K3NG keyer based around an Arduino microcomputer - the decoder in that is also very good. My K3NG is currently not in use because it is not properly cased up and was making my operating desk untidy. Sometime soon, I'll finish that off and it will become my primary decoder...

Martin (G8FXC)
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K4AX

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #6 on: December 01, 2022, 11:57:05 AM »

CW skimmer isn't half bad. 
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N6YWU

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #7 on: December 01, 2022, 03:49:37 PM »

Not for linux, but for macOS and iPhone/iOS (which are BSD Unix derivatives) I'm working on improving my SDR for RTL-SDR rtl_tcp servers; and the beta test version includes a built-in CW Morse Code decoder.  Seems to decode W1AW fast code practice sessions up to 35 WPM and CW contest exchanges at an even higher WPM.  Email me if you want to beta test.
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KD7RDZI2

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #8 on: December 02, 2022, 02:36:54 PM »

You might try Windows programmes you like under Linux,  using emulation software like wine. Some programs works immediately.
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KD7RDZI2

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #9 on: December 02, 2022, 02:46:39 PM »

nothing beats the human brain when decoding CW.
The fundamental "problem" is that Morse is a hand sent mode

73 Dave


Morse code is hand sent in the sense that the hand pushes F1 to F12 on the keyboard, at least during major contests. And that can be decoded rather well by software. Even an untrained operator may correct or skip the uncorrected characters. If both you and your PC cannot copy just ask agn, ?, nr.
« Last Edit: December 02, 2022, 03:06:25 PM by KD7RDZI2 »
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KC3TEC

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Re: CW decoder for SDR? for Linux, but better than fldigi
« Reply #10 on: December 02, 2022, 08:07:57 PM »

Well... might there be certain settings which will help FLdigi work better at decoding CW? There are a lot of FLdigi settings which I don't yet understand how to use.

Only very fast sampling and processing, but it still wont be perfect because you must account for error correction.

While electronics are indeed fast, they are light years behind the speed of thought.
A practiced ear and mind can decipher code even with minor errors
Even then the hand can send only at a finite rate. And it is much, much slower than the mind.
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