Well, You are all correct... as usual "it depends"; in this case it depends on mode, band and operating style.
If I were, for example, using the "panoramic" type operation to look for a snap-shot of what was going on in cw, rtty or psk modes using Multipsk, I would opt for a fairly wide open filter of 3000 Hz....if I then started a qso I would drop in a filter of as narrow as possible for the given mode. For some modes this is obviously not an option (of yet) as one is not decoding, say Olivia, on a panoramic waterfall (visual ID's using CMT Hell excluded as are RS ID's). I find the more narrow than stock filters are the reason I use the IC-746 Pro over my IC-718; but milage varies from person to person. If all I was to operate was 6 meters, using most any digitial mode, there would be little need for a more narrow than SBB filter as there is (sadly) no qrm. On the other hand, using a digital mode on 80 in the evening without a more narrow filter would make things even more miserable. 73 Bill N9DSj --- In digitalradio@yahoogroups.com, "Andrew O'Brien" <[EMAIL PROTECTED]> wrote: > > I agee with Danny and don't quite "get" what Leigh is saying. > > > Dave's question is an interesting one because with my 3-week old DSP capable > rig I, have been experimenting with the issue Dave raised. I have the > ability to go down to 50 Hz IF-DSP filtering , but to be honest I find the > digital bands to be so sparsely populated that I have not needed to use th > filtering tha much. I'm waiting for a big contest to test this further. > > With regard to what Leigh is saying, I have been anxious to find out if my > variable AGC and/or DSP filtering offer any significant improvement over the > infamous "strong PSK signal 'desenses' other signals in waterfall" issue. > With my admittedly little playing around, I have not found the AGC settings > to make that much difference. I just noticed a strong PSK31 signal way out > at the 1700 Hz mark on my waterfall. When he transmits my Multipsk > waterfall darkens considerably. Turning a fitter on , in this case > 1000Hz, eliminates the strong signal at 1700 and the waterfall at the lower > end returns to normal. I still have not figured out how to best "center" > on the remaining waterfall with software commands to center on 1000 or 1500 > Hz, since these commands center you to parts of the band that you may have > filtered out. Still need to find time to practice more. I guess I need > filter out the strong signals, shift the remainder of the waterfall so that > it is centered on 1000 Hz an then use "align" or "center" macros. Sounds > like work though. > > Dave, I think 500 Hz should be all you need for all but the most unusual > situations.
