On Sat, Jan 16, 2010 at 8:10 AM, k5nwa <k5...@sbcglobal.net> wrote: > At 02:54 PM 1/21/2007, Tayloe Dan-P26412 wrote: >> >> Suppose the receiver does an average noise level calculation over the >> sampled bandwidth (min function?) and then set an AGC threshold above >> that point (10 db?). If the signal falls into the range of the noise >> level up to the new AGC threshold, the signal comes through linearly >> amplified. If the signal is higher than the threshold, AGC is applied >> to keep it from blasting and or distorting away. >> >> This might give the best of both worlds where the noise floor is not >> needlessly amplified, producing a "quiet" receiver, but where AGC kicks >> in when needed to keep large signals under control. This could produce >> audio that is much more "listenable" than the current AGC amplified >> situation and more controllable than the "AGC OFF" alternative. >> >> - Dan, N7VE > > The AGC in the Flex can be adjusted so you get a very quiet receiver that > signals just pop out when you tune them. Phil Hartman wrote a paper on the > AGC that you may find interesting, it's not your average AGC mode.
Hi Cecil. I think that you and Dan are actually agreeing, but coming at it from different viewpoints. I have been wondering about this as well and was going to post the same query. I know that my setting of the AGC threshold control in PowerSDR is *very* algorithmic. By ear I reduce the AGC-T control to produce about a 10dB reduction in noise on the band and at the time I am operating. In other words, I want the maximum gain of the receiver to be set to the dynamic range of the receiver in the current conditions, i.e. the range from noise floor (internal noise + atmospheric noise) to the BDR. If you think about it, what Dan has suggested/proposed is to do just that. The difference is, he suggests sampling the noise floor across the FFT range and then having the software set the AGC-T. This makes a LOT of sense to me. There would still be a knob, i.e. the operators preference for the level above the noise where the AGC threshold will be set, but that only needs to be set once (as opposed to every time bands and conditions change) so can live in the configuration area, not on the front panel. Great idea Dan. -- 73 de Brian, WB6RQN/J79BPL _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kc.flex-radio.com/ Homepage: http://www.flex-radio.com/ Message delivered to arch...@mail-archive.com
