Hello Geri,
I have heard of Cool Edit but I have not downloaded it, but I will have a
look using the URL you have provided.
I am trying to make standalone programs using C++ Builder for convenience.
For LF work I think that we need to slow down the audio at least 8 times
into 250Hz and I think I know how to try this. However, I do not think that
the LF people are particularly interested in this which is why I am replying
to you direct. There may be more demand from the meteor scatter people who
need to slow High speed Morse down but without the drop in pitch that they
get now by using recording techniques. I think I will tackle that one first.
73
Lionel
G3PPT
-----Original Message-----
From: 'Geri' Kinzel, DK8KW <[email protected]>
To: INTERNET:[email protected] <[email protected]>
Date: Sunday, December 24, 2000 1:29 PM
Subject: LF: Slow Voice experiments
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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