At my noisy qth, I have to use the noise blankers. This results in strong signals OUTSIDE the filtered bandwidth, anywhere in the 96kc passband, modulating the noise blanker INSIDE the filtered frequency range. It often causes desired signals in the filtered range to be unreadable.
I would gladly trade spectrum display sensitivity outside the filter range for narrow passband filtering pre blanker or detector. It would make the difference between being able to hear stations or not. Of course it would need to be -Optional- and ideally, adjustable. You could probably have a separate detector drive just the spectrum display if you wanted to maintain a full range spectrum display with the pre-filter on. Maybe there is a way to apply the noise blanker to only the filtered audio in DSP? I've tried a range of settings for the blankers, sampling rates and agc, but can't get rid of this problem. 73' -Jeff On Tuesday 10 April 2007 06:02:08 pm Jim Lux wrote: > At 03:29 PM 4/10/2007, Toby Deinhardt wrote: > >Hi, > > > > > Q35. What changes were made to the internal (non software) bandpass > > > filters on the FLEX-5000? > > > > > > A. First, all filters are low pass instead of band pass. We don't > > > need band pass filters in the FLEX-5000 SDR architecture. Also, the > > > transmitter and both receivers have their own independent filter > > > banks. Nothing is shared in the FLEX-5000. > > > >The acid test for any RX here in Europe is its large signal behavior. > >I know of no RX with a Scheunentor frontend which survives this test. > > > >I'm not sure that this is a good idea.... > > > >How this is going to work with numerous 9+40 to 9+60dB signals (I'm > >not joking) in the MW, 49m and 41m bands, I would like to know. > > What might be interesting is something like a rapidly tunable > preselector that gets commanded by the radio.. on receive, one might > be able to do it with some varactors and inductor. Sort of standard > practice on things like spectrum analyzers, where they use a YIG > preselector, but at HF that YIG sphere would be the size of a bowling > ball, or larger. It would be a tricky design so the varactor didn't > cause more problems than it solves. > > One of the mfrs has a little stepper motor driven LC preselector, but > that seems a bit archaic.. > > I've been thinking about this in another connection...but, since it > doesn't have to handle Tx power, there's a lot of possibilities.. > Would you prefer a bunch of narrow band notches, or a really sharp > band limiting to the ham band, or a tunable selective filter (say 3-5 > kHz wide?) > > > Jim, W6RMK _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
