This week, I built a small interface to get on and operate PSK. Neat mode.
I downloaded and installed Digipan software to use on PSK. Digipan (and
many other PSK software) features a waterfall, a continuously scrolling
window showing a panoramic view of the radio's bandpass. PSK signals are
represented as yellow (on my PC) lines and Band noise is represented by blue
or yellow noise across the screen. A linear scale across the top of the
waterfall goes from 0 to 3000 Hz. Generally most all of the PSK activity
seems to take place centered around about 1,000 Hz.
One of the things I found to be of particular interest to me was seeing the
effects of my Omni VI's filters and the effects of the variable BP. By
switching various filters (2.4, 1.8, 500, 250) in and out, the effects were
visually and dramatically presented in the waterfall.
Not only did I hear signals disappear as I narrowed the bandwidth, but I saw
them disappear from the waterfall as well. As the PBT was varied, I could
see the BP moving across the screen accordingly, seeing (and hearing)
signals appear as the BP moved over them and seeing them disappear as the BP
moved off of them.
Also, watching the notch filter effect on the screen was very interesting.
As the notch moved through the bandpass with the baseband noise and signals
present, it was represented as a black 'stream', essentially nulling out the
noise/signals in the stream. Pretty cool. The Omni VI's notch filter is
always on. But, generally when not using it, it can be set outside the
passband.
This was a very interesting side benefit of using PSK to not only be able to
hear the effects of the filters and notch, but to see the effects as well.
73,
dale, kg5u
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