DuBose Walt Civ AETC CONS/LGCA wrote: > My uncle, Charles Sumner Williams (author of Introduction to the Optical > Transfer Function), who taught radio at Scott Field during WWII and retired > from TI said that the problem with "computer" signal detection (we were > discussing CW) was trying to duplicate with a computer what the human brain > could do was difficult. However, once you succeeds, the computer is likely > to be able to do the job better. > > I did not realize until much later, that in part he was talking about how our > brain, perhaps acting as a quantum like computer, takes current and past > information to predict the future and that the brain can be trained to reject > certain sounds, patterns and the like. I believe this is correct. You cannot do this job correctly and only treat it as a conventional signal processing problem. FEC works on digital signals by building in redundancy. Better decoding of CW would make use of the existing redundancy rather than just "is it on or off?". CW sending words clearly has significant "Markovity" in the actual transmitted tones. To not take advantage of the predictability of the next character or element given those elements just preceding it would be folly. In the case of distorted signal or signal in noise or interference, this is a Hidden Markov process. The algorithms for treating this under certain assumptions are well known and understood. iNTUITIVELY, one looks at the possible outcomes for the next element and picks the best outcome given the observations. One should use signal before AND after current element under consideration as the "observations". The brain certainly uses this. I struggled like mad when I was attempting to learn to copy faster morse before I got my extra in the early 1970's. My speed really took off when I relaxed, allowed myself to fall a little bit behind. Now it is clear I am using signal information before and after the object I am attempting to decode. Then the speed really went up when I started copying words and phrases and not letters.
> Mathematics remains the fundamental science used to analyze and explain the > complex algorithms of human speech. Virtually every branch of pure and > applied mathematics has proved to be useful in these efforts. Where the > human brain is a biological computer, the computers humans build simply tries > to emulate this function...the human brain is our basis and model. > Understanding this concept will greatly enhance our ability to create a > better HF modem. > > Walt/K5YFW > > The mathematics of this kind of language modeling applied to signal processing is simply fascinating. 73's Bob N4HY -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman "You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat." - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) <*> To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
