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From: root@zswamp.uucp (Geoffrey Welsh)
Newsgroups: comp.dcom.modems
Subject: Auto Baud
Message-ID: <7205.28053F0F@zswamp.uucp>
Date: 12 Apr 91 00:16:01 GMT
Organization: Izot's Swamp BBS (FidoNet), Kitchener, Ontario
Lines: 31


 >From: hoskins@iccgcc.decnet.ab.com

 >Has anybody heard of an algorithm called "Auto Baud"? What 
 >this is, if I
 >understand correctly, is a method for a initializing a modem 
 >or serial
 >port by trying to sync up to a known incoming data stream 
 >(all the same
 >character, I think) and guessing at the baud rate, parity, 
 >etc. until the data stream is received.

   I've seen some software that picks a baud rate and waits; if a framing 
error occurrs, it switches.  I would think that one should start at a high 
baud rate and hope that incoming data words would be long enough to cause 
framing errors until the correct word size is chosen (though careful 
selection of data might conceivably prevent this).  The incoming caller may 
send BREAK signals to force a change of baud rate.

   Of course, this doesn't address the possibility of line noise causing an 
error and triggering a switch *from* the correct baud rate!
 

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