[Lowfer] Narrow IF Filters with Argo

[Les Rayburn]

All points made by John, Lyle, and others are well taken. Mark, you'll
soon learn that these guys are the technical guru's while I am basically
an appliance operator, cheerleader, and historian. When in doubt, listen
to those guys!


What I was trying to express (but didn't do well) is that newcomers should
start out with lots of bandwidth and then work their way into something more
narrow. I've done lots of A/B testing with the JDH beacon, using attenuation to
take the signal down well below the noise floor. In almost every case, I never
saw any real difference in copy with my 250hz IF filter switched in or out.


As folks have correctly pointed out, the problem is that a nearby noise signal
could pop up in the middle of an overnight session and overload the system.
Using the narrow IF and keeping the receivers AGC on (and in fast mode)
certainly helps to reduce the chances of that.


While I am "attending" one of my sessions, I usually leave the filters and 
the AGC
off and just let Argo do it's thing. For one thing, I can often "hear" the 
signal I'm
looking at this way and quickly determine if it's a modulated signal or just
man made noise. And by turning off the AGC, I've seen some very small
benefits in weak signal recovery.


By long winded point is that I've never seen a narrow IF filter make much
of a difference in QRSS reception. I don't really understand what I'm
doing. Don't try this at home. Your mileage may vary.


73,


Les Rayburn, N1LF



Les Rayburn, director