Wayne, This is great stuff, but.... Suggestion for Elecraft: make a K3 panadaptor and a KW automatic, SO2R amp higher priorities! 73, Andy, AE6Y ----- Original Message ----- From: "Terry Schieler" <terry.schie...@wirelessusa.com> To: "'wayne burdick'" <n...@elecraft.com>; "'Dan Romanchik KB6NU'" <kb...@w8pgw.org> Cc: "'Elecraft Mailing List'" <elecraft@mailman.qth.net> Sent: Thursday, January 22, 2009 1:04 PM Subject: Re: [Elecraft] CW copy: Wayne's solution
> > Wayne Burdick wrote: > > Humans use lexicographical and semantic clues to fill in dropped CW > characters, and computers can do the same. But this goes way beyond the > simple signal processing used in, say, the K3's present CW decoder or > the one used in HRD. (I studied natural language recognition in college > and was anxious to play with either neural networks or traditional AI > methods as the foundation for CW decoding, but my other classes got in > the way :) > > One idea from the early days of AI is the so-called "blackboard" model. > Imagine a garbled sentence on a blackboard, with various experts > offering their opinions about what each letter and word is based on > their specialized knowledge of word morphology, letter frequency, > syntax, semantics, etc. You weigh these opinions based on degree of > confidence, and once there's enough evidence for a letter or word, you > fill it in, which in turn offers additional information to the > highest-level expert, who might be considering the actual meaning of a > phrase. His predictions can then strengthen the evidence for lower > level symbols, and so on. Such methods are very algorithm-intensive, > but might be useful for some aspects of CW stream parsing. > > A neural network could handle this, too, and has the advantage of > self-organization. This is how I'd approach it (assuming unlimited free > time--not!). You could use any of several different types of networks > that have been proven successful at NLP (natural language processing). > > For example, you might take the incoming CW, break it into samples (say > a few samples per bit at the highest code speed to be processed), shift > the serial data representing 5 to 20 letters into a serial-to-parallel > shift register, then feed the parallel data to the network's inputs. Or > you could use a network with internal feedback (memory), with just one > input, which itself could be "fuzzy" (the analog voltage from an > envelope detector) or digital (0 or 1 depending on the output of a > comparator, looking at the CW stream). The output might be a parallel > binary word, perhaps ASCII, or a single output with multiple levels, > where the voltage itself represents a symbol. > > To make this work, you need at least three things: an input > representation that provides adequate context (e.g., if you want to > decode a letter, the input should contain at least a few letters on > either side of the target); a sufficiently complex network; and a large > corpus of clean text with which to train the network (probably > thousands of words, drawn from actual on-air content). > > One classic method of training the network involves placing known-good > signals at the input, then comparing the desired outputs to the actual > outputs, and "back-propagating" the resulting error through the > network--from outputs to hidden layers to inputs--so that the network's > nodes gradually acquire the proper "weights." Once the network has been > trained to the point that it perfectly copies clean CW, you can then > present it with a noisy signal stream. A well-designed network would be > able to correct dropped CW elements or even letters if its internal > representation is highly evolved. The network will have learned > language-specific rules, and you don't have to know how it works, > anymore than you know how your own brain does it. > > The actual implementation is left as an exercise for the reader. If you > come up with an algorithm written in 'C', let me know and I'll try to > port it to the K3's PIC. > > Wayne > N6KR > > > Sounds good, Wayne. When can you have it done? Upper right hand button > would be my choice. > > 73 de Terry, W0FM > > > > > _______________________________________________ > Elecraft mailing list > Post to: Elecraft@mailman.qth.net > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
