Dummy's Guide to Noise Reduction

[GW0ETF]

To all NR 'confusees',

Since getting my K3 #145 I've seen the discussion about Noise Reduction
go round the block 2 or 3 times and I have to wonder if folk bother
reading the FAQ which I've copied below...

<<<<<<<<<<<<<<<<<<<
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.
 >>>>>>>>>>>>>>>>>>>

Seems clear to me; I'm no expert (DSP 'dummy') but it tells me for one
thing that adaptive dsp filtering is going to work better with cw than
phone. There is more on it in 'Operating Tips' and somewhere Lyle gave a
good explanation of the different settings available but I can't find it
now - anyone know whether it's lurking somewhere on the web site?

Have fun (I am.....!)

--
73, Stewart Rolfe, GW0ETF (K3 #145)
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[Arie Kleingeld PA3A]

K3 arrived today.

Took UPS express 34 hrs & 14 mins from Aptos,CA  to  Barendrecht,NL.
(NL = Netherlands, Europe)

73,
Arie PA3A

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[G3MLO]

  The message is spend time just listening to the band and get a feel of the
  many aids available to achieve the very best performance that will suit
  you style of operating, it took me 6 months to master my Orion and I think
  with the continued development of the K3 we need to take note of all the
  release notes as Stewart had pointed out, Thanks Stewart 73 Peter G3MLO

GW0ETF wrote

To all NR 'confusees',

Since getting my K3 #145 I've seen the discussion about Noise Reduction
go round the block 2 or 3 times and I have to wonder if folk bother
reading the FAQ which I've copied below...

<<<<<<<<<<<<<<<<<<<
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.
 >>>>>>>>>>>>>>>>>>>

Seems clear to me; I'm no expert (DSP 'dummy') but it tells me for one
thing that adaptive dsp filtering is going to work better with cw than
phone. There is more on it in 'Operating Tips' and somewhere Lyle gave a
good explanation of the different settings available but I can't find it
now - anyone know whether it's lurking somewhere on the web site?

Have fun (I am.....!)

--
73, Stewart Rolfe, GW0ETF (K3 #145)
_______________________________________________
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Post to: [e-mail]
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Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

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Elecraft web page: http://www.elecraft.com