Lionel, G3PPT wrote:
As far as slow audio goes, I wonder if it would be possible to record 2
kHz
bandwidth speech into a .WAV file at 44100Hz and then alter the sampling
frequency in the file header to 11025Hz. Playing this would result in the
speech with a duration four times as long but in one quarter the
bandwidth.
The frequency band would span 1 to 500Hz, so this would need to be
transposed up to 300-800Hz in order to go through an SSB filter.
Reception
could be by similar techniques to those used in QRSS.EXE referred to
above
but with a further transposition to restore the original pitch. With the
SB16 card, it would be possible to play a .WAV file at 5513Hz though a
250Hz
bandwidth but not all soundcards allow the choice of non standard
frequencies
Lionel,
Cool Edit 2000 (http://www.syntrillium.com/) has a transpose feature, in
which you can transform the speed and make a recorded message four times
longer, reducing the bandwidth. You can do the opposite, too.
I tried to push a 100 to 900 Hz (so within the DL 800 Hz bandwidt
limitation) message created with Cool Edit through my PA/antenna
configurarion ... sounded terribly awful and distorted! I suppose, the
antenna bandwidth is too small and the PA not really linear enough ... I
will do futher experiments.
Please everyone feeling disturbed please feel free to tell me immediately
... I don't want to block the entire band ...
Best 73
Geri, DK8KW (W1KW)
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