On 10/26/2010 5:28 PM, The Smiths wrote: > If find that in Noisy conditions I like to lower my side tone down to 380Hz, > yet when I'm in a casual QSO I find that I receive better at about 450Hz.
Yes. There's another psychoacoustic principle at work here, as well as an electronic one. 50 Hz is a larger percentage of 350 Hz than of 600 Hz. This gives the ear/brain more to work with in discriminating tones (and noise) that are closer in Hz, and it also makes the filter have less percentage bandwidth, which means that, all things being equal, it has better performance than a filter designed for the higher audio frequency. Ah, you say, these are digital filters, so it doesn't matter. Wrong -- digital filters are simply digital emulations of analog filters, and the math that makes analog filters do what they do has the same effect on the emulations! So there's no free lunch -- the digital filters are simply far more flexible, because you're building with bits, not Ls and Cs. :) And there's a third VERY important operational principle, which i think you and others have alluded to -- all of this must be done VERY QUICKLY -- the entire QSO may only last 15 seconds, and you can easily lose a CQ frequency while taking too long to dig a weak one out of the mud. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
