[Lf] Software-based VLF Receiver]

[Andre' Kesteloot]

DL4YHF at 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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