[linrad] Re: [winrad] Re: Noise Reduction

["Rein A. Smit" <ix.netcom.com; rein0zn@xxxxxxxxxxxxxxxx>]

 Alberto, Leif and Others,

Last night Roger, W3SZ placed some .wav files on his site at:
  
    http://home.comcast.net/~w3sz/index.html

and I was able to run them on Winrad with the delta44 card. at 96 kHz

The first time after all this time I listened to a signal at  96 kHz 
sampling
rate, because of  effective pass band in my receiver  frontends.
Always checked whether the card would sample at the different frequencies.
but always listened on 8 kHz

I was really surprised about the audio quality of the detected signals from
Roger's files.

Most likely, it is some oversight on my site, though I have been aware 
of Leif's comments
about the wideband requirements for Linrads noiseblanker to work to its 
fullest
capabilities.

So far I have always used linrad and winrad with output from a ssb 
receiver ( 1.8 kHZ
filter ) not realizing that this might not be the optimum conditions for 
the noise reducer
and noise blanking to perform..

Both Leif and Alberto mention the bandwidth issue in the operating 
instructions
but as said I did not realize up till now,  the importance.

As more and more amateurs will try the programs it might be useful to
put some more emphasis on this, stating that narrow band filtering of the
incoming audio signals could or will seriously deteriorate  performance.

73 Rein W6/PA0ZN








i2phd wrote:

> --- In winrad@xxxxxxxxxxxxxxxx W6WO <W6WO@xxx> wrote:
>  
>
> > FB  Alberto and all. I have placed a file to the group to help 
> > examine the performance of winrad filtering and de-noising,  It's 
> > only about 1.2 M so I have placed it in the files section. It was 
> > recorded from a Tentec Omni VI with a 250 Hz filter and with the
> > Onmi NR off.  It is at 22050 Hz sampling rate and 16 bit mono
> >    
>
> Ron,
>
>   the noise reduction algorithm needs to look at a bandwidth as wider
> as possible. Don't use a narrow filter in your Tentec. Winrad is meant
> to be placed after a direct conversion receiver that has *no* bandpass
> filters.
>
> 73  Alberto  I2PHD
>
>
>
>
>
>
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>  


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