Message-ID: <4BA7F044.4010301@freenet.de>
Date: Mon, 22 Mar 2010 23:33:40 +0100
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Subject: Re: VLF: Whistlers again
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Hi David,

Cutoff frequencies are 16 kHz in the analog filter (before the stero FM 
transmitter, which doesn't like signals close to 19 kHz), and something 
like 14.7 kHz in the digital filter. Furthermore, frequencies above 13.5 
kHz are also removed by the MP3 encoder, before the stream is sent to 
Paul's VLF audio server at 32 kSamples/second and 64 kBit/second on 
avrage. So "what you hear" is actually limited to 13.5 kHz.

The configuration of the filter currently in use is here now: 
http://www.qsl.net/dl4yhf/vlf_reception/VLF_Receivers.html#DSP

73 and successful VLF listening,
  Wolf
(whistler activity slight increasing again; but here time to go zzzz... :)


David Weinreich schrieb:
> Wolf,
>  
> What is the cutoff frequency for the high pass filter in your setup??
>  
> Vielen dank,
>  
> David Weinreich
> WA2VUJ/3