[Elecraft] Dummy's Guide to Noise Reduction

[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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