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Re: Voice over data
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[email protected] once said:
RI> Eric Hughes wrote:
RI> > the great voice-over-data protocols and products introduced by
RI> > Intel, Rockwell, ZyXEL and others at Comdex which will make
RI> > Voice-PGP so much easier
RI> >
RI> > As I understand these voice-over-data products, the voice goes over
RI> > analog, added to the modem signal. The modem signal is interpreted,
RI> > and then reconstructed and subtracted from the incoming signal,
RI> > leaving voice. Very clever, but insufficient for secure phones.
RI>
RI> I don't think that's how they do it. As far as I know, most methods
RI> multiplex
RI> digitized audio with the data. One system used by some people in India
RI> provides
RI> a dynamic combination of fax, (digitized) voice and data, depending on the
RI> throughput - eg vox/9.6 data if 14.4kbps, fax as well if 19.2, etc.
RI>
RI> While Intel and others are proposing standards, ZyXEL does it with software
RI> along with a voice card or possibly RJ11 input. A friend of mine saw a demo
RI> of it at Comdex, on an old 1496E (16.8 kbps zyxel to zyxel). The new v.34
RI> does
RI> 28.8k - lots of room for clear digitized voice and high speed data.
RI>
RI> This is exactly why I thought it would make secure voice easier, if not
RI> secure
RI> phones (who wants to lug a modem and PC around as a 'handset'?).
RI>
RI> I'll be testing some Onetics Rad VFAST modems this week, which apparently do
RI> digitized voice over v.34 as well.
>
>You wouldn't have the directory name as well, by any chance?, David.
The IGP files are available at a32.cc.umist.ac.uk in the /network/ftp/igp
directory.
There are two versions of the program available:
1. igp8_10x.zip for 8 bit sound (on 8 or 16 bit sound cards)
2. ig16_10x.zip for 16 bit sound cards. Better quality, but more data
to transfer so a bit slower.
the latest source code is also available as igps_10x.zip.
Paul Archard (IGP UMIST Distribution acting Project Manager)
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[email protected] Cryptoanarchy, MDMA, Tekkkno, SL-1200
<blink> <A HREF="http://xs4all.nl/~kafka">Kafka's home page</A>
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