Message-ID: <477688FC.4040402@freenet.de>
Date: Sat, 29 Dec 2007 18:50:52 +0100
From: =?ISO-8859-1?Q?Wolfgang_B=FCscher?= <dl4yhf@freenet.de>
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Subject: Re: LF: [137] Grabber , Europ and America
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Hello Jean-Pierre,

Thanks for running the grabber (which I frequently visited in the past 
weeks).
I don't think that the dynamic range of the spectrum display in SpecLab 
has changed that much,
but there may be some points to consider:

- use one of the FFT windows with a large stopband attenuation.
There is a nice comparison of different FFT windows here:
http://en.wikipedia.org/wiki/Window_function

( -> the "Hann" window is ok, but avoid the "Rectangular" window).

- reduce the soundcard volume (if you use a soundcard for input) so the 
maximum peak level stays at least 6 dB below the clipping level (use one 
of the "monitor scopes" to see this).

- the noiseblanker may help to reduce the effect of "dog-boning" if the 
strong signal uses hard on/off-keying (quite likely for class-C amplifiers).

Besides that, V2.71 "beta 3" is available, but I wouldn't recommend it 
for unattended operation because it is not thoroughly tested (yet). 
Murphy will make sure it will crash only after something interesting 
appeared on the screen ;-)

All the best for 2008 to everyone,
  Cheers, 
      Wolf .



Jean-Pierre Méré schrieb:
> Hello  all on LF ,
>
> For better managing the strong signals , I passed the grabber to the
> version 2.7b20 of SpectrunLab ( thank you Wolf for this splendid tool )
>  I hope for that I did not make errors, that seems to function correctly
> until there! one will be fixed tomorrow !
>
> grabber at :  http://jpmere.online.fr/Grabber/Grabber.htm
>
> 73 Jean-Pierre  f1afj   JN06ht