[Lowfer] BPSK31

[John Andrews]

Stewart,

> 5. Generate the PSK audio at a high frequency, e.g. 18 kHz, at a 48 kHz
>    sample rate.  Combine with carrier in a double-balanced mixer.  If
>    you are trying to Tx on 185 kHz, your LO would be at 167 kHz, so the
>    image is at 149 kHz.  This is far enough away from the desired output,
>    that one high-Q tuned circuit should be an adequate filter.  The
>    second filter is your antenna :)

Actually, I think Dex had good luck with 5 kHz, and did both WOLF and Jason
that way.

I'm sketching out a simpler phasing exciter than the one I built. The audio
phasing only has to be accurate over a fairly narrow range compared to
voice, so there will only be a limited number of critical components.

Darn, but I do like your suggestion of quadrature sound card outputs,
though!

John A.