You might find this paper interesting:
Rabson, John and Hugo (1996) 'Some Experiments in Speech Bandwidth Reduction
', CREG Journal 24, pp3,6.
If you have difficulty getting hold of the article please let me know.
----- Original Message -----
From: Holger 'Geri' Kinzel, DK8KW <[email protected]>
To: <[email protected]>
Sent: Monday, December 18, 2000 7:55 AM
Subject: LF: DX Cluster spots for 10/17Dec at GB7DXM
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 ...
73 de
John Rabson G3PAI
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