[Lf] slow audio ?

[Andre' Kesteloot]

"Holger 'Geri' Kinzel, DK8KW" wrote:

> Hello Alan and all other LF-friends,
>
> >On Sunday an unusual noise aleted me to a PSK31 signal on 137.6, I swapped
> >programs to see Geri just finish working DL7YA on X-mode, and then
> continue
> >with Wolf DF0WD also cross-mode.
>
> Thank you for your report on my PSK31 signal and the log you send me. It
> shows, that also PSK31 is good for long-distance QSOs close to the noise.
> The QSO with Wolf, DF0WD, by the way, was a full PSK31/PSK31 QSO. Wolf was
> only running lower power than usual, bus he is one of my nearest neighbors
> (about 110 km away), so I copied his signal 599. The QSO with DL7YA was
> PSK31/CW, quite an unusual combination, but we had a lot of fun ...
>
> I managed to get my new Hagenuk EX-1001 QRV on 136 in SSB, producing about
> 1 or 2 Watts from an AD2030 (tnx Rich, OM2TW for the schematics, it woks
> great, no problem!). To avoid multiples of my audio signal appearing within
> the band, I uses 135.500 kHz upper sideband and fed a 2000 Hz PSK31 signal
> into it, ending with a more-or-less clean 137.500 kHz signal. As soon as my
> PA is back on the air again, I will continue to test various computer
> generated modes that require SSB.
>
> Another thought: we in Germany are allowed to use any mode with a maximum
> bandwidth of 800Hz. I know that normal 2.1 kHz wide SSB signals havne been
> transmitted in the early days of LF in the UK. Has anyone ever thought of
> "Slow-Audio" instead of Slow-CW? My idea is to use an audio editing program
> such as Cool Edit (available as shareware) and reduce the running speed, so
> that a normal sharply filtered (the filter is a build-in feature of Cool
> Edit)  2.4 kHz audio signal is compressed into 800 Hz or an even smaller
> bandwidth. The same software could then be used to expand the signal again
> and make it audible. I plan to do some local testing (and yes: I will run
> those on reduced power using time slots when normally there is no traffic,
> I do not want to block the entire band with such a funny signal ...) to see
> what can be achieved ...
>
> Best 73
>
> Geri, DK8KW (W1KW)