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I, just as a hobby project, am writing a program for decoding Morse code.

I am not a ham, but generally interested in radio and programming. I have a first version of the project, but it failed to decode the signal in this recording.

The length relation between the dash and the dots is far from "standard" and the length of the dashes varies wildly.

Is this type of signal common or should I say "skip this, too weird"?

I also see _....._ in the recording, which I don't recognize as a character: does it have some special interpretation?

Edit: Fun to read about the "banana boat swing". And to get confirmation about my suspicion that a "bug" was used from the consistent length of the "dits". I once tried to learn Morse, but I gave it up. Was unable to get hang of reading. For sending I tried both straight key and bug. And according to my mentor my "fist" was quite good. The aim of the project is not only to read the charters. But also to decode all the prosigns to make the conversation more understandable for an outsider.

73 :)

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  • $\begingroup$ fldigi does a tolerable job of decoding this, so you can aspire to do the same :) $\endgroup$
    – hobbs - KC2G
    May 8, 2019 at 14:07
  • $\begingroup$ Your last paragraph really should be moved to a comment here. When you do that, I'll reply to it and give you a suggestion. $\endgroup$
    – Mike Waters ♦
    May 9, 2019 at 16:56

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That is Morse code, in Norwegian, being sent with a "bug" (Vibroplex type mechanical key). The two operators are LA6UH and LA7JS. Probably not something you want to figure out how to decode with a machine, but the ops' "fists" make them very recognizable to those who know them.

LA6UH gives a clue in his bio, where he writes:

I spent a couple of years of my youth roaming the seven seas as a radio officer.

I worked as a research assistant on the Honduran island of Utila the summer after graduating high school. The only reliable communications with the mainland were via the commercial radio shack a few hundred yards from our residence, from which they also served the Merchant Marine and security establishments. Those ops had the true "banana boat swing," virtually indecipherable to my ears, even though I was already a Vibroplex veteran. The ops identified each other immediately by "fist," much as any of us recognize people we know by the timbre and cadence of their speech.

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    $\begingroup$ Fun to read about the "banana boat swing". And to get confirmation about my suspicion that a "bug" was used from the consistent length of the "dits". I once tried to learn Morse, but I gave it up. Was unable to get hang of reading. For sending I tried both straight key and bug. And according to my mentor my "fist" was quite good. The aim of the project is not only to read the charters. But also to decode all the prosigns to make the conversation more understandable. 73 :) $\endgroup$
    – enocknitti
    May 8, 2019 at 6:36
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    $\begingroup$ @enocknitti I was lucky to learn Morse Code at an early age, which also fueled an interest in languages. Fifty years later, CW is still my preferred mode. Recent band conditions and antenna restrictions are encouraging new hams I know to take it up. If you agree, please tick the "check mark" next to this answer to take your question off the "unanswered" list. Good luck! $\endgroup$
    – Brian K1LI
    May 8, 2019 at 9:35
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That sounds like code sent from a bug to me: machine-generated dits, hand-generated dahs. The operator seems fairly good actually; those things take lots of practice to use well, and I've definitely heard much worse code from bugs.

I can see how writing software to decode that would be challenging, but code like that won't seem unusual or more-difficult to copy to any long-time Morse operator. This is one area where machine learning and software are only now just catching up to an ability skilled humans have had for over a century.

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    $\begingroup$ Machine-generated dits and hand-generated dahs are exactly how the old Vibroplex "bugs" functioned. A mechanism on the key using a weight and spring generated the dits for high-speed CW. $\endgroup$
    – Mike Waters ♦
    May 9, 2019 at 15:41
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I'm not an expert but it sounds like a regular CW to me.

The problem with decoding CW automatically is that it's synthesised by people. The speed (letters per minute) can change, the length of "dits" and "dahs" can change, etc. Whether you should support decoding such style of CW depends only on the time you are willing to invest in the project.

The code ..... is a regular code for number 5.

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  • $\begingroup$ Strange, what wrote was ( dash dot dot dot dot dot dash ) with underscores as dash, This site seems to remove underscore from text $\endgroup$
    – enocknitti
    May 7, 2019 at 19:37
  • $\begingroup$ I'm not familiar with this code. Maybe OP made a mistake and what he or she meant was _...._ which is a code for a dash or minus sign. It could also be two symbols without a proper pause between them, e.g. 6 (_....) and then A (._)or B (_...) and then U (.._). $\endgroup$
    – Aleksander Alekseev - R2AUK
    May 7, 2019 at 19:55
  • $\begingroup$ @enocknitti -- two underscores format the text between them as italic. To get more details about the Markdown conventions, click the "help" link when you write a comment. $\endgroup$
    – Pete NU9W
    May 8, 2019 at 11:54
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I can't listen to the recording at the moment, but what you describe sounds very much like a "bad fist" -- an operator whose sending isn't particularly standards compliant. Incorrect dot-to-dash ratio and varying dash length are characteristic of sloppy sending (though it's barely possible you recorded someone using the old American Morse, which had two different dash lengths and different ratios and spacing from International Morse).

One of the biggest challenges of writing a Morse reader program is handling the inconsistencies of hand-sent Morse. Even the best operator will have some variation in ratio and spacing -- this is the "fist" that lets an experienced operator recognize another ham from the sound of his Morse. Even highly developed software doesn't always manage to interpret some fists that an experienced human operator will read without problems. In some ways, it's like handwriting recognition in software (but at least without the image processing and need to handle both manuscript and cursive).

Whether you want to try to write your software to handle a broad range of fists, or only something close to the "perfect code" a machine would send, is up to you. The latter is far easier -- but the former is more useful, and a much greater challenge.

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To my ears, that's not all that strange. I was able to casually copy some words by ear. I would guess that it was sent using a hand key, rather than a computer or electronic keyer.

I have some unfinished CW RX Pascal code here --somewhere-- that I wrote many years ago to compensate for variations in dit, dah, or spacing lengths. I suggest you think about writing something similar. It used if..then 'greater or less than' character length statements to correct and print the characters.

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  • $\begingroup$ The code may very well be in the rtty-pc directory in www.w0btu.com/files/... section. Let me know if you can't find it; I may have it on one of my older computers here. $\endgroup$
    – Mike Waters ♦
    May 7, 2019 at 19:24
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    $\begingroup$ Thanks for your responses ! My code allows for quite a lot of variation in dit, dah, or spacing length. But not as much as in this example. The "dits" do not vary( with a few exceptions). "dahs" vary qutie a lot. From 3 * dit-len to almost 6 * dit-len. If this kind of "sloppy" keying is common I have to do some rethinking. Untill I found this recording my main problem was to "extract" the signal from the noise when bad "conds" Btw: here is a graph of the unknown code, dropbox.com/sh/adoatd80zm0i37d/AADsdp7Az9SEgu5X7Vq6_yhIa?dl=0/… $\endgroup$
    – enocknitti
    May 7, 2019 at 20:31
  • $\begingroup$ @enocknitti There is some noise in between characters. Perhaps you can figure out a way for your code to ignore that. $\endgroup$
    – Mike Waters ♦
    May 9, 2019 at 16:54
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Having just listened to the recording, I concur with the other answers that say this is Morse code generated by a mechanical "bug" key, where the dots are generated by the key, and the dashes are generated manually by the operator. I have never tried using one of these keys, but I would imagine that they take a bit of getting used to. But one day if you used one every day as your only way of communicating, you might be as proficient as these operators.

They are obviously very comfortable talking to each other, and very comfortable with each other's "fists". I disagree with the answer saying this is a "bad fist", since both operators seem fine talking to each other, and with a bit of practice you would easily be able to understand what they are saying (assuming you can read Norwegian, which I can't!).

Interestingly, and counterintuitively, the mechanical "bug" is where the convention of using the 'thumb' paddle for the dots and the 'index finger' paddle for the dashes on a paddle key comes from - one would expect to use the index finger for the dots and the thumb for the dashes, as you need more precision for the shorter elements than you need for the longer ones. But on a mechanical "bug" you don't need much precision for the dots, since they are being generated by the key - and it is more important to use the extra precision for the dashes.

Finally, to answer the question about the _...._

There are two possible answers for this:

  • it could be that the user is sending _..._ but missing the number of dots, so it comes out with four dots instead of three. The symbol _..._ is the "equals sign" = and is commonly used as a 'break' in text, usually to indicate that there may be a pause following, but that you're not finished yet.
  • It is also possible that the user intended to send _...._ which is a dash - because he is a way more experienced operator than most, and actually knows most of the punctuation symbols that most people never use in standard conversation.

I tend to favour the second explanation, after listening to the audio.

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  • $\begingroup$ Just a note: it is 5 dots $\endgroup$
    – enocknitti
    May 8, 2019 at 7:14
  • $\begingroup$ Interesting - I heard 4 in most cases $\endgroup$
    – Scott Earle ♦
    May 8, 2019 at 7:34
  • $\begingroup$ A graph of the unknown code :dropbox.com/sh/adoatd80zm0i37d/AADsdp7Az9SEgu5X7Vq6_yhIa?dl=0/… $\endgroup$
    – enocknitti
    May 8, 2019 at 9:21
  • $\begingroup$ I think the thumb is used for the dits because it takes a good whack to get the springing pendulum moving, and the thumb is much better suited to a sideways whack than the index finger. (I've played with someone else's bug, but never owned one or tried to become proficient on one.) $\endgroup$
    – rclocher3 ♦
    May 8, 2019 at 16:41

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