Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2 9/18/84; site ecsvax.UUCP
Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!ecsvax!hes
From: hes@ecsvax.UUCP (Henry Schaffer)
Newsgroups: net.dcom
Subject: FASTLINK (tm) "10,000 bps or faster" modem
Message-ID: <720@ecsvax.UUCP>
Date: Fri, 8-Nov-85 14:49:47 EST
Article-I.D.: ecsvax.720
Posted: Fri Nov  8 14:49:47 1985
Date-Received: Wed, 13-Nov-85 07:40:39 EST
Distribution: net
Organization: NC State Univ.
Lines: 40


  I got the glossy 4 page brochure from Digital Communications Associates,
Inc. (the IRMA people) about their FASTLINK (tm) 10,000 bps modem.  It 
also has 300 and 1200 compatibility, but I thought people might be 
interested in some of the "fast" features.

  "Data transmission at 10,000 bps or faster."  N1
  "Asynchronous dial-up connection."  
  "Automatic error detection and correction."  N2

N1- inside it says "Poor quality lines may result in lower transmisssion
     speeds."
N2- Correction is done by the sending modem adding a CRC to each packet,
     and then, "If the receiving modem detects an error, it requests a
     retransmission to insure error-free transmission."

  This modem sends out a bunch ("hundreds") of tones, decides which ones
are acceptable for use, and uses these.  When the S/N ratio is bad, fewer
bits are encoded on each tone, and this is varied incrementally every few 
milliseconds.  Also, while this modem is full duplex, it adaptively varies
how much of the transmission capacity is allocated to each direction.  (So
I imagine that the "10,000 bps or faster" speed is reached with nearly all
the data going in one direction.)

  They call this a "Packetized Ensemble Modem".  It comes bundled with a
special version of Crosstalk (r) for IBM PC/clones.  The modem has a
superset of Hayes commands, and gives access to its registers containing
"phone line characteristics such as signal-to-noise ratio, number of
retransmitted packets, bits per packet, and frequency offset."  It is not
clear how big the packets are, two places say they vary, and one
place says they don't.  No mention is made of performance in
a character echo environment.  All this fancy stuff is done by "multi-
processor power, capable of handling over 7" MIPS.

  The company is at 1000 Alderman Dr., Alpharetta, GA  30201  (404)442-4000
and the list price of the stand-alone version is $2395.  (The PC card version
is $400 less.)

--henry schaffer  n c state univ
Standard Disclaimer - and I've never even seen one of them (the modems).