Maybe the additional noise in the stages between where the filter would be in IF and where it is in AF? I know I'm thinking of multi-stage RF/IF/AF superhets and that might be what is tripping me up when it comes to a single conversion SDR capability. Maybe there is no difference? Or maybe components that make up a filter in an IF stage are more effective (higher Q) than in an audio stage?
73, Kev K4VD On Wed, Aug 23, 2017 at 7:58 PM, Fred Jensen <k6...@foothill.net> wrote: > Doesn't appear to say very much. Other than the BW difference [RF/IF BW > might be more than ultimate AF BW], and provided that the demodulated audio > is free of IMD and other obnoxious distortion, I don't see why NR at AF > wouldn't be essentially the same as at IF. Obvious differences in the > mechanisms to do it, and I'm sure there are dozens of nits that will be > picked over this, but if you can find the signal in the noise [or the noise > obscuring the signal] at the IF frequency, I can't see any reason why you > can't do it at AF just as well. > > 73, > > Fred ["Skip"] K6DGW > Sparks NV DM09dn > Washoe County > > On 8/23/2017 4:06 PM, Walter Underwood wrote: > >> Discussion appears to be here. >> >> https://uk.groups.yahoo.com/neo/groups/SNR_group/info?v=1&t= >> directory&ch=web&pub=groups&sec=dir&slk=363 < >> https://uk.groups.yahoo.com/neo/groups/SNR_group/info?v=1&t >> =directory&ch=web&pub=groups&sec=dir&slk=363> >> >> wunder >> K6WRU >> Walter Underwood >> CM87wj >> http://observer.wunderwood.org/ (my blog) >> > > ______________________________________________________________ > 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 > Message delivered to kkinde...@gmail.com > ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
