Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!bloom-beacon!think!ames!sdcsvax!ucbvax!ANDREW.CMU.EDU!mw3s+ From: mw3s+@ANDREW.CMU.EDU (Martin Weiss) Newsgroups: comp.dcom.modems Subject: Re: 9600 baud standards Message-ID: Date: Tue, 15-Sep-87 09:05:39 EDT Article-I.D.: andrew.oVHHgXy00Uhqwk80Ck Posted: Tue Sep 15 09:05:39 1987 Date-Received: Thu, 17-Sep-87 02:26:34 EDT References: <171@tahoma.ARPA> Sender: daemon@ucbvax.BERKELEY.EDU Organization: The ARPA Internet Lines: 18 There are two standards for 9600 bps modems: V.29 for leased line modems and V.32 for dialup. V.29 has been around for a number of years (since 1976, I believe) and V.32 has been around since 1984. V.29 is well entrenched as a 9600 bps leased line standard. It has been adapted by some manufacturers to dialup use by using it in a pseudo-duples mode. V.32 is a very new standard. It uses echo cancellation to separate the originate and receive channels and trellis coding for performance improvement. Full V.32 modems are expensive at this time, because the chip sets for echo cancellation aren't cheap. Some manufacturers use a sub-set of V.32 for their modems, and others use proprietary techniques. Hayes, for example, does not adhere to V.32 to the best of my understanding. My guess is that V.32 will emerge as the dominant standard in dialup 9600 bps modems, but that it will take a while. This will be due in large part to the cost of implementing echo cancellation.