Hi Arlen - I, too, seek just such a general guide for using the
various noise reduction features on modern transceivers, but have yet to
find one. Transceiver user manuals are typically pretty lean on real
world explanation - they enumerate the features, point out what button
or knob makes an adjustment, but there is a paucity of explanation on
how and when to use those features on the air. This is a problem with
many other features on these radios. Moreover, the manuals rarely
explain how an one feature relates to the another noise reducing
features, including the NB Noise Blanker, BW Bandwidth, PBT Pass band,
RF-Gain, and other controls, which, when used together, work pretty well.
Modern transceivers like the K3 have different tools for different
problems. I recommend a detailed web search for articles and comments
that explain how these various systems work, in general, and which work
best on what types of noise, in particular. Eventually, you will
assemble enough information to better understand how these features
operate and interact. I have yet to find a single, comprehensive
explanation in real world terms... and I have looked!
Sometimes a combination of adjustments will get the click. Sometimes
nothings gets the click. This research will pay dividends and you will
learn about the K3 and other radios as well.
In any case, there are no free lunches, these tools alter incoming
signals, causing, in turn, some level of distortion and impose unwanted
digital "artifacts" - hopefully resulting in greater intelligibility,
but with some fallout or deleterious impact in the signal. You trade
off one for the other, and hopefully don't go too far and make things
worse, which is easy to do. Used in moderation, audio quality is
sacrificed to some degree to achieve better intelligibility.
The first thing you must determine is which type of noise is tackled by
each noise reducing feature. For example, and it varies from rig to
rig, but generally (speaking in very general and not scientific terms
lest I generalize too much) - DSP NR attempts to reduce random noise
like atmospheric static and general hiss which covers a weak signal. The
NB Noise Blanker typically reduces repetitive pulse type noise like
ignition sparking, and some NB circuits are geared more to reducing the
heavier pulsing of radar systems, like what SW listeners call the
Russian Woodpecker. The AN or Auto Notch seeks out and removes one or
more constant tones, like when someone is tuning his antenna tuner right
over your QSO. A manual notch does that manually, you gotta adjust it
out, frequency and bandwidth are user selected. The PBT or Pass band
Tuning control allows you to shift the receiver pass band left of right
to avoid a problem signal on one or the other side of the signal you
want. You get less of the desired signal, but maybe none or far less of
the offending signal that way. RF-Gain can often be used to lower
signal and noise (so to speak) and you end up with less noise and less
signal, but maybe a better signal-to-noise ratio where noise is less
noticeable against the resulting signal volume.
You should research how each one works, on transceivers generally, and
the K3 in particular, and EXPERIMENT with each individually and blended
with others for best advantage, each situation may vary from another in
some way.
There are few concise explanations, so it may take some time to assemble
a comprehensive explanation, but the effort will pay dividends on your
time investment.
Good luck.
--------------------- K8JHR ---------------------
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