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How efficiently does Morse code encode letters?
- gumby 10y agoIt's not just frequency/density but also the value for forward error correction: codes (code points) that can more easily be mistaken for others should have such different semantics that an error is obvious. For example though e and a are the two most common letters in the English language, perhaps use the shortese code for e and the next shortest for q, so that a misunderstanding causes "went" to become "wqnt" rather than "want. And indeed perhaps e does not deserve the shortest code because of its importance.
- sp332 10y agoEnglish is already pretty redundant, you only need about one bit per character for most text. You can see this if you compress a block of English text; you'll probably get 12.5% of the original size which is one bit per eight-byte character.
- gumby 10y agoYes, but morse is being decoded in realtime by a piece of meat (a trained NN admittedly, but different senders have different "fists" so there's a lot of variation). The problem is that some character errors are ambiguous.
- sp332 10y agoTrue, but even though Morse is a denser encoding than ASCII, there is often enough redundant information to infer the correct letter from context. A/E seems a really bad case, but I don't think we have to go all the way to A/Q to fix it.
- ddingus 10y agoHwoever thows errs pars fiarle easly People on both ends tend to adapt quickly. A few brief, known exchanges will typically result in longer ones going fairly well. And "the meat" does all sorts of stuff. Names get shortened or changed for brevity or style. Gark might be gary, for example. One group I observed used a lot of first letter strings: BBQSTSP? Y K Barbecue, same time same place? Yes OK
- ddingus 10y agoHwoever thows errs pars fiarle easly People on both ends tend to adapt quickly. A few brief, known exchanges will typically result in longer ones going fairly well. And "the meat" does all sorts of stuff. Names get shortened or changed for brevity or style. Gark might be gary, for example. One group I observed used a lot of first letter strings: BBQSTSP? Y K Barbecue, same time same place? Yes OK
- e28eta 10y agoI never got around to actually learning Morse Code, but I think the English language corpus is probably dramatically different from the messages that are actually sent via Morse Code. My understanding is that abbreviations are commonly used, greatly skewing the letter frequencies: https://en.m.wikipedia.org/wiki/Morse_code_abbreviations https://en.m.wikipedia.org/wiki/Morse_code_abbreviations
- topspin 10y agoThere are also a large number of Q codes that cover practically everything related to communication and also naval, aeronautic and rescue concerns. Today much of this isn't in use, but amateur radio operators use a subset of these routinely; a typical fast Morse code exchange is often composed almost entirely of Q codes and call signs. [1] https://en.wikipedia.org/wiki/Q_code https://en.wikipedia.org/wiki/Q_code
- khedoros1 10y agoI became aware of Q codes through their use in the book Seveneves. It provided a brief glimpse into a subculture that I've never had much contact with, and I ended up in a bit of a Wikipedia crawl.
- monochromatic 10y agoI'm glad you commented. I was sitting here racking my brain, trying to remember what book I'd read that involved Q codes. Then I saw your comment, and it was indeed Seveneves.
- FiatLuxDave 10y agoI was lucky enough as a kid to inherit my grandfather's collection of old sci-fi books. I first became aware of Q codes through the short story "QRM Interplanetary" from 1942 (https://en.wikipedia.org/wiki/Venus_Equilateral https://en.wikipedia.org/wiki/Venus_Equilateral). I find it interesting that Q codes have changed so little over the last century. I have some ham radio friends who will use Q codes when talking face-to-face with each other, and the codes they use are basically the same ones from the original list.
- tzs 10y agoThe article is looking at efficiency in terms of time to transmit a given message. For that you want to assign the shorter codes to the symbols with the highest frequency. Morse did a decent job of that, except that assigning '---' to 'O' seems way off, since '---' is in the top 5 for longest code length, whereas 'O' is one of the 5 more frequent symbols. I wonder what would change, if anything, if instead we considered things from the receiving side, and put a bound on the acceptable error rate? That '---' for 'O' really stands out when listening to code. The only other letter that was a '---' in it is J ('.---'), which only occurs about 2% as often as 'O'. Maybe 'O' being so distinct and easy to hear, and frequent enough that you will have an 'O' every 10 or so characters, helps keep the listener synchronized? Early Morse code was sent fully by hand, and so the timing would not be precise. The timing is supposed to be, in units of the length of a dot: 1 for a dot, 3 for a dash, 1 for the space between adjacent dots and dashes within a character, 3 for the space between characters in a word, and 7 for the space between words. A good, experienced operator would hit that timing very accurately, but less experienced operators could be quite a bit off. Someone whose timing is off might shorten the gap between characters enough that it might run dashes from the end of one character and the start of the next together. For example, in the word 'awkward', the 'wk' sequence becomes '.-- -.-' and if the person did not give as big a gap as they should between the words, you could run the trailing '--' from the 'w' and the leading '-' from the 'k' together giving a '---', but even in that situation I don't think it would sound like an 'O', because with an 'O' you go into it trying make 3 evenly spaced things, and we are good at that. We might get the spacing off, but we'll get it off the same way uniformly throughout the 'O'. An accidental 'O' from running two things together won't have that uniformity, and so I think it would stand out. In other words, I'm guessing that the apparently anomalous assignment of a seemly too long code to 'O' actually servers to make communication more accurate in the presence of inexperienced senders and receivers.
- diego898 10y agoIf you liked this article, you should check out a blog post giving a visual introduction to information theory[1] by Chris Olah [1]: https://colah.github.io/posts/2015-09-Visual-Information/ https://colah.github.io/posts/2015-09-Visual-Information/
- WalterBright 10y agoI have patents 6418323, 7831208, 6850782 which cover using Morse code on a phone to send and receive text messages. The advantage is you don't have to look at the phone's display when composing or 'reading' text messages. The phone can be in your pocket and you can send/receive messages without bothering others. Obviously, it never caught on, but I thought it was a fun idea.
- jlgaddis 10y agoThis is actually something I would use -- say, while driving. Emoji would probably throw me off, though. I learnt Morse at age 12 or so, actually used it regularly on amateur radio for quite a while, but haven't used it for probably about 20 years. I can still "read" it when I hear it, without even thinking about it.
- w8rbt 10y agoMorse code on an apple watch: https://www.youtube.com/watch?v=wydT9V39SLo https://www.youtube.com/watch?v=wydT9V39SLo
- 5bolts 10y agoi use a variation of this. With custom "ring tones".. vibration patterns. I encoded my common contact's names as morse. dad, mom, sis, matt, work.. etc.
- leovonl 10y agoSOS was meant to be easily recognizable and trivial to generate: ... --- ... --- ... --- ... (and so on)
- sverige 10y agoActually, it is sent sequentially as a single nine-digit signal, then repeated. Graphically this looks like ...---... ...---... ...---... and so on. Incidentally, graphical representations of Morse code are weak tea. It has to be heard to be understood.
- jonah 10y agoNote that in addition to the Morse Code that roughly equates to "printable" ASCII, there are prosigns [procedural signals] which are control characters that affect things like transmissions and message formatting. https://en.wikipedia.org/wiki/Prosigns_for_Morse_code https://en.wikipedia.org/wiki/Prosigns_for_Morse_code
- toddh 10y agoThey also had specialized code books for different industries so that increased compression quite a bit.