From: wcs@anchor.ho.att.com
Date: Mon, 23 Aug 93 10:21:34 PDT
To: geoffw@nexsys.net
Subject: Re: "Secure Voice"
Message-ID: <9308231713.AA01938@anchor.ho.att.com>
MIME-Version: 1.0
Content-Type: text


geoffw@nexsys.net (Geoff White) writes: 
> 	Anybody know about the voice capabilities of the ZyXel class modems?
> 	I own a ZyXel 1496E which can digitize voice and also transmit
> 	voice data that has been digitized.  It would be easy to
> 	first encript this stream before sending it out.
> 	The 1496E+ also support CELP (or is it (CLEP?) but that one
> 	cost about $400.  (The 1496E is around $300) It also is a 14.4 K
> 	baud modem and does FAX. 

The ZyXel has a 68xxx and a DSP chip.  It's able to digitize and compress voice,
and also to play back digitized voice, and also to do 9600/14400 modeming,
but it can't do all three at once.  To build a secure voice phone with Zyxels,
you'd need either 2 or 3 modems - one to handle the modem functions,
one to compress the voice, and either the same or a separate one to play voice.
But it's a good start.

What I'd like to see is a SoundBlaster followon with a DSP chip.
It IS possible to get DSP boards for PCs and I think for Macs,
so you could build a system easily enough with a DSP board and a SoundBlaster,
but the last time I checked, the DSP boards tended to be expensive
and packaged with lots of fancy waveform analysis tools.

		Bill Stewart