Message-ID: <000a01c1cf2f$4cff5920$1700a8c0@home>
From: "Dave Pick" <g3yxm@wireless.org.uk>
To: rsgb_lf_group@blacksheep.org
References: <7D653C9C42F5D411A27C00508BF8803DCB9A09@pdw-mail-r1.dstl.gov.uk>
Subject: LF: Re: Soundcard Mods
Date: Tue, 19 Mar 2002 10:17:39 -0000
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Andy.

The clock for the integrated sound chip may be derived from other system
clocks.
Better to disable the internal audio and mess about with a Ł10 PCI sound
card!
If you're getting ambitious there are quite a few "pro" soundcards out there
which sample up to 96kHz, input filtering is probably quite good at 22kHz
though...
See HHB.co.uk and other pro-audio dealers.

73
Dave
G3YXM.

----- Original Message -----
From: "Talbot Andrew" <ACTALBOT@dstl.gov.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, March 19, 2002 9:59 AM
Subject: LF: Soundcard Mods


> Has anyone tried changing the clock source on a Soundcard for a different
> frequency ?  For a  job here at work we need to sample more accurately
than
> the usual crystal oscillator (does this sound familiar ?) and at different
> sampling rates.  It would be ideal if we could push it to 50kHz, but 25kHz
> and 12.5kHz would do, as well as accurate 8 and 16kHz options.  One idea
> that immediately comes to mind is to remove the Soundcard clock crystal
and
> feed in the input from a synthesizer.  Before diving inside a PC, I wonder
> if anyone has ever tried this ?  Modifying the integrated soundcard on the
> Dell machines here could prove a bit tricky just to try on spec.
>
> For LF use, how about an externally derived 1kHz sampling rate for input
> from receivers using a narrow CW filter and BFO pitch set below 400 Hz ?
>
> Andy  G4JNT - but with another hot on now.
>
>
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