[Elecraft] MCU 4.42 Beta Firmware

[David Windisch]

Hi, Adrian:

I have found:   http://www.elecraft.com/K3/K3FAQ.htm  to be helpful.

Here is a quote regarding NR:

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.

UNQUOTE

Hth.

Brgds,
Dave, N3HE
 

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