One point I've observed is the fact the noise on a given band may not be
the same from day to day, or week to week. Thus I find it necessary to
tweak the values of NR and NB for best performance. Same issues with
band to band, i.e. what I need on 80M is no where close to what I need
on 6M in terms of NR and NB. And, the NR and NB are very different in
their performance character in terms of handling noise artifacts.
One thing that also helps is to use minimum necessary RF gain and
correct utilization of Attenuation. Thus on 160M and 80M and to some
extent 40M, I use 15 dB Attenuation and reduce the RF gain a wee bit.
In doing so, the signals pop out of the noise.
A point to consider is optimum receiver performance occurs when the band
noise floor is 10 dB to 15 dB above the receiver noise floor. Since we
can't really change the receiver noise floor, we must change what is
arriving at the front end. This means some degree of attenuation and RF
Gain reduction is required. For the math.......if no signal band noise
is -97 dBm or S-5 and the receiver noise floor is - 125 dBm, a
difference of 28 dB, the receiver should have 15 dB of attenuation
activated. You can do the same with the RF Gain by reducing it about 3
or 4 S units. Too much RF gain being utilized in an attempt to hear weak
signals is not necessarily a good thing. As one goes higher in
frequency, usually band noise decreases and finally to a point where the
PRE should be used. In many cases I've heard hams describe the use of
ATTN is to prevent receiver overload. While true under some cases, most
residential QTH locations and antennas won't encounter enough signal to
overload the receiver. Thus the ATTN function is more beneficial when
used in correct receiving gain structure.
73
Bob, K4TAX
On 8/22/2017 4:11 PM, Don Wilhelm wrote:
Peter,
Since "one size" does not fit all noise sources, I believe that what
you suggest is not practical.
It may be that something could be done to provide the most useful
noise reduction for "average noise", but the closest to that right now
would be the default settings in the K3/K3S.
If you do not know what the default settings are, save your K3/K3S
configuration, then do an EEINIT (Reset to Factory Defaults), then
look at the NB and NR settings. Finally load the saved configuration
file and then set the NB and NR settings to the defaults that you
recorded. Be aware that some of the settings are per band, so you will
have to check them on each band.
That will give you a "one button" NB and NR as you might find in many
other amateur transceivers.
I am glad that the K3/K3S offers adjustability for the NB and NR
parameters. It does take some study to learn how to use the
parameters provided, but if you do that study, you will be rewarded
with good noise reduction for most any type of noise.
73,
Don W3FPR
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