From: kafka@desert.xs4all.nl (John van Goorkom)
Date: Sat, 3 Dec 94 09:58:24 PST
To: cypherpunks@toad.com
Subject: Re: Voice over data
In-Reply-To: <gate.NZuqwc1w165w@dxm.ernet.in>
Message-ID: <199412031759.AA02827@xs1.xs4all.nl>
MIME-Version: 1.0
Content-Type: text/plain


-----BEGIN PGP SIGNED MESSAGE-----

rishab@dxm.ernet.in 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)




_______________________________________________________________________________
kafka@desert.xs4all.nl  Cryptoanarchy, MDMA, Tekkkno, SL-1200
        <blink> Kafka's home page
_______________________________________________________________________________


-----BEGIN PGP SIGNATURE-----
Version: 2.6

iQBVAwUBLt7CDZRymF15lPcFAQFSsgIAhoPpWCNjRbmqu9hxrrzSKbf7uMqeJxAd
/B24tG5b5Cn3a478sg3OrMUjgF9CbsS7FZZEtKL8beOcsxS/5oaoEw==
=jMOd
-----END PGP SIGNATURE-----