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Message-ID: <3.0.1.16.19990326120204.2f67ac46@mail.cc.kuleuven.ac.be>
Date: Fri, 26 Mar 1999 12:02:04
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: Re: LF: 137 Carrier
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At 10:01 26/03/99 -0000, G3XDV wrote:
>On a similar subject, it would be really useful to be able to plot 
>signal strength against time (say, 24 hours) using a computer - for 
>simplicity it would help to use the sound card so that the same 
>connection can be used as Spectrogram. It is =just= possible to 
>do this with Spectrogram, though the amplitude resolution is poor 
>and only ten minutes or so can be moniored. Does such software 
>exist? Yes, I know I can build an A-D converter and write software 
>etc, etc but if someone has already done the work so much the 
>better.

PC sound cards are only suitable for AC, so direct reading of the s-meter
signal is not possible. The audio tone from the speaker output could be
used but  than you have to be sure that the AGC is off and even then I
doubt that the dynamic range (and linearity) is good enough for 'serious'
recording.
An alternative would be to send the s-meter signal to a V/F convertor and
then to the sound card, this would require only minimum hardware (1 IC)and
could provide thigh dynamic range and good linearity.
But we still need the suitable software, althuogh this shouldn't be too
difficult to write if you know how to read the sound card.

73, Rik