Path: utzoo!attcan!uunet!pcrat!rick
From: rick@pcrat.UUCP (Rick Richardson)
Newsgroups: comp.dcom.modems
Subject: Re: Autobaud Matching
Message-ID: <578@pcrat.UUCP>
Date: 20 Sep 88 11:31:36 GMT
References: <56.015163@adam.DG.COM> <9262@cup.portal.com>
Reply-To: rick@pcrat.UUCP (Rick Richardson)
Organization: PC Research, Inc., Tinton Falls, NJ
Lines: 26

In article <9262@cup.portal.com> thad@cup.portal.com writes:
>
>In general, autobaud detection necessitates your system being set up at some
>"high" baud and analyzing the bits that arrive when a caller types some
>character (typically a carriage return).

There are three basic methods:
1)	Pattern match the garbage that comes in on the UART.
2)	If a USART, put in sync mode, sync char==FF at a bit rate
	twice the highest speed expected.  Then collect the bits and
	analyze, and restore async mode.
3)	Use a UART which supports hardware autobaud, such as AT&T's
	ARTI (can't remember part no).

The ideal, of course, is single character autobaud.

I've implemented all three of these methods. They are listed in the
order I tried them over the years, which is also the order from
worst to best implementation.  #3 is patented (I'm one of the
inventors) and I don't know if it has been licensed to any other
chip manufacturer.
-- 
		Rick Richardson, PC Research, Inc.
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