[Elecraft] K3 Noise reduction question

[Sam Morgan]

On 8/31/2014 3:57 PM, Gene wrote:> When holding in the NR button to 
adjust noise reduction, I get
 > F1-1,2,3,4 then F2-1,2,3,4 etc for F3 and F4. Going further this is
 > repeated for NRmF5, F6, F7 and F8.
 >
 > Can someone direct me to where in the K3 manual it explains what these
 > settings mean and/or when to use NR or NRm?
 >
 > Thanks.
 >
 > Gene, W2BXR

K3 Owners Man D10.pdf
pg 6
pg 15

pg 25
<quote>
Noise Reduction
Noise reduction reduces random background noise
while preserving meaningful signals. It adds a
characteristic “hollow” sound to all signals.
NR turns noise reduction on. It doesn’t apply to
DATA or FM modes, or with AGC turned off.
Hold ADJ to display the NR setting, which is
saved per-mode. Use the VFO B knob to tailor NR
for the present band conditions. In general, the
higher the number, the more aggressive the noise
reduction. Settings F1-1 through F4-4 are
recommended. F5-1 through F8-4 use a different
algorithm, where the -x part of the setting indicates
the degree of mix between the DSP-processed and
unprocessed signals (-1 is about 50% processed, -4
is 100%). A small M appears to remind you that a
Mixed setting is in effect, e.g. NRM F5-1.
</quote>

also from: http://www.elecraft.com/K3/K3FAQ.htm

<quote>
How does the Noise Reduction work?

NR depends on correlation of the present input with previous input. The 
system does not actually provide Noise Reduction; it provides Signal 
Selection. In other words, its default is to pass nothing at all. It has 
to believe there is a signal present, and then it builds a filter, or 
set of filters, around the spectral components of the signal it thinks 
is there.
Random noise has no correlation, voice has moderate but not perfect 
(unless you whistle a pure tone) and CW has excellent correlation.  As a 
result, noise is heavily suppressed (no filter is built to pass it), 
voice is partially suppressed (hence it needs some additional gain to 
compensate for this effect so the same AF level will produce about the 
same audio level with a moderate S/N speech signal) and CW is hardly 
suppressed at all (hence it does not need any gain boost).
NR is not recommended in Data Mode.  Data is already getting a matched 
filter in the demodulator. You might lose a few symbols as the NR 
settles around the signal, and it might suppress a very weak signal that 
you could otherwise copy.
NR in the end is intended for modes you listen to.
</quote>

lastly I saved this gem of a post from Jack WA9FVP

====
Re: [Elecraft] [K3]Noise Filter (NF) ADJ
wa9fvp Thu, 27 Dec 2012 16:19:36 -0800

There's no documentation but as far as I can tell--

F1-x through F4-x defines the amount of noise reduction or how aggressive
the filter attacks the I.F. noise.  F5-X through F8-X defines the amount of
reduction and the level that's mixed with the filtered and non-filtered I.F.
Note that "m" which means "mix" will appear after F5-X and above.

X defines the delay.  Delay is the amount of time it takes for the filter to
converge on a non-sinusoidal signal or the noise.   The higher the number,
the longer it takes for the noise to reduce to a low level.

I hope this helps.

Jack WA9FVP

F1-x through F4-x are for CW
F5-x through F8-x are for SSB
====

-- 
GB & 73
K5OAI
Sam Morgan