Software-based VLF Receiver

Tue, 29 May 2001 08:45:24 -0400

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DL4YHF@aol.com wrote:

> Hello group,
>
> Because of the coming test transmissions on 16kHz and 17.2kHz, I did a
> few
> tests with 'direct reception' of LF signals up to 20 kHz using only
> the PC, a
> soundcard, a piece of software and a few metres of wire. The results
> are
> good, and may be useful for some of you.
>
> The basic concept:
> - soundcard running at 44100 Hz sample rate
> - input signal is converted to 650Hz audio with an image-rejecting
> mixer
>  (phase method, using a Hilbert transformer)
> - output from the mixer (650Hz) filtered with IIR or FIR filter,
> 100Hz bandwidth or less
> - output from the filter passed to soundcard output (in real-time).
>
>
> You need a PC with at least 166MHz, Spectrum Lab V1.65 beta5 (new).
>
> The problem is that not all soundcards are suited for this "full
> duplex"
> operation (or, to be precise, the control program does not allow the
> proper
> settings). I did a few tests on some PC's, on two it worked
> immediately and
> one (a notebook) had kind of a 'feedback' problem.
>
>
> More info can be found here:
>  http://www.qsl.net/dl4yhf/vlf_rcvr.html  .
>
> The 'special pre-release' of Spectrum Lab V1.65 beta5 can be loaded
> from:
>  http://members.aol.com/dl4yhfhamsoft/spectr_i.zip
>
> I am very interested in the 16kHz transmission from GBR, hope it's
> going to
> work. Thanks for passing the info about GBR, Mike.
>
> User feedback welcome. Good luck, cu on 136kHz,
>   73's Wolf (DL4YHF, DF0WD).

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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
&nbsp;
DL4YHF@aol.com wrote:
<blockquote TYPE=CITE>Hello
group,
Because of the coming test
transmissions on 16kHz and 17.2kHz, I did a few
 tests with 'direct reception'
of LF signals up to 20 kHz using only the PC, a
 soundcard, a piece of software
and a few metres of wire. The results are
 good, and may be useful
for some of you.
The basic concept:
 - soundcard running at 44100
Hz sample rate
 - input signal is converted
to 650Hz audio with an image-rejecting mixer
 &nbsp;(phase method, using
a Hilbert transformer)
 - output from the mixer
(650Hz) filtered with IIR or FIR filter,
 100Hz bandwidth or less
 - output from the filter
passed to soundcard output (in real-time).
 &nbsp;
You need a PC with at least
166MHz, Spectrum Lab V1.65 beta5 (new).
The problem is that not all
soundcards are suited for this "full duplex"
 operation (or, to be precise,
the control program does not allow the proper
 settings). I did a few tests
on some PC's, on two it worked immediately and
 one (a notebook) had kind
of a 'feedback' problem.
 &nbsp;
More info can be found here:
 &nbsp;<A HREF="http://www.qsl.net/dl4yhf/vlf_rcvr.html">http://www.qsl.net/dl4yhf/vlf_rcvr.html</A>&nbsp;
.
The 'special pre-release'
of Spectrum Lab V1.65 beta5 can be loaded from:
 &nbsp;<A HREF="http://members.aol.com/dl4yhfhamsoft/spectr_i.zip">http://members.aol.com/dl4yhfhamsoft/spectr_i.zip</A>
I am very interested in the
16kHz transmission from GBR, hope it's going to
 work. Thanks for passing
the info about GBR, Mike.
User feedback welcome. Good
luck, cu on 136kHz,
 &nbsp; 73's Wolf (DL4YHF,
DF0WD).</blockquote>
</html>

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