
Re: Sending Messages in Morse Code
Posted:
Aug 2, 2000 2:18 AM


On Tue, 01 Aug 2000 22:18:42 +0200, MokKong Shen <mokkong.shen@tonline.de> wrote, in part:
>Do I understand correctly that you want to transform a random bit >sequence (almost uniformy distributed) into a sequence of Morse >code symbols and study the optimal transformation?
I'm assuming I have a bit sequence that is precisely uniformly distributed, and my goal is to find the optimal transformation of that sequence  within limits to the complexity of the transformation used  into Morse code.
>I admit that >I haven't fully understood your article, hence the question: Do >you keep the set of the original Morse code symbols or do you >consider possible extensions, i.e. introducing more symbols?
I do keep the original Morse code symbols. I note that if I introduced more symbols, even symbols from the original Morse code, such as those for digits, this would result in changes to the transformation.
Normally, in constructing a Huffman code for the English alphabet, for example, one has probabilities for symbols, and then uses those probabilities to construct symbols. Supposing one already has a fixed set of symbols of different lengths: can one go in reverse, and determine how to use those symbols optimally?
That is the question I address, and I find that I have to determine the potential efficiency of a code using those symbols before I can compute the probability for each symbol that would make the code optimal. This requires solving a fancy polynomial equation. And this also means I have to take into account persymbol overhead (as opposed to perbandwidthunit or perbit overhead, which being constant can be ignored). Then I can construct a Huffman code based on those probabilities normally, although I am using it in reverse to express an input in bits as an output in symbols of differing probability.
I just don't remember seeing this kind of thing done before, and so it seems an illustration of the math involved in finding optimal codes of a different kind.
John Savard (teneerf <) Now Available! The Secret of the Web's Most Overused Style of Frames! http://home.ecn.ab.ca/~jsavard/frhome.htm

