Re: [Elecraft] Re: Homebrew Autotuner
Joseph: Genetic Algorithms would be an extremely inefficient method for solving such a problem where the objective value is so easily measured and the direct effects of the arguments of the objective function (capacitance and inductance) are so easily determined. Wayne's solution is relatively direct and clearly effective. Kevin Rock's proposal, using some method of steepest decent is also of interest. However, anyone who has used a transmatch with tunable input and output will know there arise situations where simple iteration between the two tuning capacitors does not simply walk down a SWR valley. Occasionally one must significantly off-tune one cap to get a lower reading with the other. This, then, is a situation where first derivatives are inadequate and second derivatives are best brought into play. Steepest decent is a "first-derivative only" algorithm. Some form of a DFP or, better yet, Newton's method -- ones that also use the Hessian information -- would be of interest in this context. However, all these kinds of optimization routines are assuming continuous variability of the arguments, C and L. With a very finite number of values of C and L to consider, a tree network with branch-and-bound really seems the way to go. Switches in values that increase SWR are pretty effective means for pruning branches off the tree. best wishes, david belsley, w1euy On Sep 14, 2005, at 9:57 AM, Sanger, Joseph wrote: Stephen Kercel's suggestion to use a Genetic Algoirthm is brilliant ... this sounds like a perfect application for these astounding and amazing techniques. I have had two passions in my life (at least, PG-rated) ... ham radio and genetic algorithms ... own every book ever written on GA's as well (have even read most of them!) ... (not a lot of real world experience with GA's of course ... I am more of a theoretician!). The beauty of the GA's, loosely modeled on the way real DNA and natural selection work, is that they often finds good empirical solutions to difficult problems like tuner settings optimization, without the need for the articulation of the exact methodology used. In other words, all of the factors that Wayne wrestled with become moot ... the GA will find good solutions to the problem without all the intellectual knowledge of antennas and radio physics. I would encourage any of you who want to have some real fun to search google and read about GA's. Joseph Sanger, M.D. WB2SSB --- This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain information that is proprietary, confidential, and exempt from disclosure under applicable law. Any unauthorized review, use, disclosure, or distribution is prohibited. If you have received this email in error please notify the sender by return email and delete the original message. Please note, the recipient should check this email and any attachments for the presence of viruses. The organization accepts no liability for any damage caused by any virus transmitted by this email. === === ___ 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
Re: [Elecraft] Re: Homebrew Autotuner
Toby: Good point. 73, Steve AA4AK At 04:10 PM 9/14/2005 +0200, Toby Deinhardt wrote: As much as GAs are fun and very powerful, I do wonder about the amount of time it might need using say a population of 50 and 100 generations. Assuming 100ms for switching and mesurement -> 100ms * 50 * 100 = 8Min 20Sec. Not to mention the amount of memory needed. Most controllers do not have gobs of memory. vy z3 de toby ___ 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
Re: [Elecraft] Re: Homebrew Autotuner
As much as GAs are fun and very powerful, I do wonder about the amount of time it might need using say a population of 50 and 100 generations. Assuming 100ms for switching and mesurement -> 100ms * 50 * 100 = 8Min 20Sec. Not to mention the amount of memory needed. Most controllers do not have gobs of memory. vy z3 de toby ___ 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] Re: Homebrew Autotuner
Stephen Kercel's suggestion to use a Genetic Algoirthm is brilliant ... this sounds like a perfect application for these astounding and amazing techniques. I have had two passions in my life (at least, PG-rated) ... ham radio and genetic algorithms ... own every book ever written on GA's as well (have even read most of them!) ... (not a lot of real world experience with GA's of course ... I am more of a theoretician!). The beauty of the GA's, loosely modeled on the way real DNA and natural selection work, is that they often finds good empirical solutions to difficult problems like tuner settings optimization, without the need for the articulation of the exact methodology used. In other words, all of the factors that Wayne wrestled with become moot ... the GA will find good solutions to the problem without all the intellectual knowledge of antennas and radio physics. I would encourage any of you who want to have some real fun to search google and read about GA's. Joseph Sanger, M.D. WB2SSB --- This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain information that is proprietary, confidential, and exempt from disclosure under applicable law. Any unauthorized review, use, disclosure, or distribution is prohibited. If you have received this email in error please notify the sender by return email and delete the original message. Please note, the recipient should check this email and any attachments for the presence of viruses. The organization accepts no liability for any damage caused by any virus transmitted by this email. == ___ 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
Re: [Elecraft] Re: Homebrew Autotuner
wayne burdick wrote: It was a wonderful, hair-pulling, sleep-depriving, learning experience that I wouldn't deny anyone by giving away the details ;) Wayne, you're a sick, sick man... but we love you! :-) -- "Nosey" Nick Waterman, Senior Sysadmin. #include [EMAIL PROTECTED] Santa is so jolly is because he knows where all the bad girls live ___ 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] Re: Homebrew Autotuner
On Sep 13, 2005, at 11:08 PM, Vic K2VCO wrote: I bet Wayne knows a good algorithm! Indeed I do. And it took several weeks of serious R & D and coding the first time we developed an ATU (KAT2). Among other things, the code uses four tuning phases, each with different granularities; time-based SWR target adjustment; hand-tuned, pseudo-grayscale switching of latching relays; SWR-based look-ahead tree pruning (borrowing extensively from game theory); scaled L-C stepping near local minima; and, when possible, L-C range prediction based on band information. It was a wonderful, hair-pulling, sleep-depriving, learning experience that I wouldn't deny anyone by giving away the details ;) 73, Wayne N6KR --- 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
Re: [Elecraft] Re: Homebrew Autotuner
Instead of an exhaustive search, you might try a genetic algorithm. 73, Steve AA4AK At 11:51 PM 9/13/2005 -0400, Mike WA8BXN wrote: Don - If you can easily tune the tuner by hand I always teach my programming students to just watch themselves manually performing the task, then write down a set of instructions so someone else could do that, and then write the program to follow those steps. Seems to me an exhaustive search trying all combinations has to find the lowest SWR, but that would take time. You could perhaps first run through your smart search method and if it gets close enough stop there, and if not, try all values. If you could get an approximation of the complex impedance of the load (not exactly sure how to do that offhand) you could then calculate what is approximately needed to best match it, and search around there. I will be interested in reading the ideas of others on this topic! 73/72 - Mike WA8BXN ---Original Message--- From: Don A few months ago I maintained a brief correspondence with some on this list with an interest in a homebrew balanced autotuner. The project is nearing the point where I will be installing it into a K2 case. At the moment, though, I am having trouble coming up with a software algorithm that finds minimum swr and this message is a request for suggestions. ___ 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
