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From: phil@east.Berkeley.EDU (Phil Lapsley)
Newsgroups: comp.dsp
Subject: Re: DSP board with telephone interface
Keywords: DSP telephone modem
Message-ID: <1991May29.203601.19054@agate.berkeley.edu>
Date: 29 May 91 20:36:01 GMT
References: <14157@exodus.Eng.Sun.COM>
Sender: root@agate.berkeley.edu (Charlie Root)
Reply-To: phil@east.Berkeley.EDU (Phil Lapsley)
Organization: University of California at Berkeley, EECS Dept.
Lines: 45

If you don't mind building some simple hardware, you can build the
telephone line interface yourself and connect it to a DSP and AD/DA board of
your choosing.  Cermetek Corp. makes some fairly cheap (between $30 and
$100) phone line interface modules (e.g., their "CH1811 Registered
Telephone Line Interface").  They take in a telephone line (tip and
ring) and split it into receive and transmit audio channels (1 vpp in
and out), and also give you TTL level controls and indicators for off
hook, ring, etc.  The only thing you really need is power, a case, a
handful of resistors, some wire wrap, and maybe an op-amp to convert
the audio levels to the range of your AD/DA board.  We're in the
process of building one for our DSP lab here, to be connected to an Ariel
ProPort AD/DA board and a BCE/Ariel S56X SBus DSP56001 board.

If you want to avoid building the (analog) hardware, you might check out
Atlanta Signal Processors, Inc.'s (ASPI) "Serial Voice Interface" box
with the telephone line interface option.  This is a small box that
has a TI TLC32040 14 bit codec, telephone line, and telephone handset
interface.  The data from the codec is output via RS 422, and it's then
your problem to get it into the DSP of your choice.  The price?  $895.00
(as of December 1, 1990).  Seems kinda steep, but some people really hate
to wire wrap.  :-)  Also, note that I have no experience with this board,
and I'm basing the above on product literature.

You might also ask Ariel Corp. if they're working on something similar;
I've heard rumors that they are.

Addresses:

	ASPI
	770 Spring St.
	Atlanta, GA 30308
	(404) 892-7265

	Ariel Corp.
	433 River Rd.
	Highland Park, NJ 08904
	(908) 249-2900

	Cermetek Microelectronics
	1308 Borregas Ave.
	P.O. Box 3565
	Sunnyvale, CA 94088-3565
	(408) 752-5000

Phil Lapsley		phil@ucbarpa.Berkeley.EDU	...!ucbvax!phil