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Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!floyd!harpo!ihnp4!ihuxf!parnass
From: parnass@ihuxf.UUCP
Newsgroups: net.micro
Subject: baud != bits per second
Message-ID: <1720@ihuxf.UUCP>
Date: Thu, 19-Jan-84 15:24:52 EST
Article-I.D.: ihuxf.1720
Posted: Thu Jan 19 15:24:52 1984
Date-Received: Sat, 21-Jan-84 02:19:10 EST
Organization: AT&T Bell Labs, Naperville, IL
Lines: 38


x
       Folks always seem to confuse "bits per  second"	(bps)  with
       "baud." Some related information:

	 a.  Baud is a unit of signaling rate, and already contains
	     units of time.  Talking of	"baud rates" makes about as
	     sense as talking about "knot rates."

	 b.  Baud is its own plural, hence there is no such word as
	     "bauds."

	 c.  The signaling rate	of most	1200 bps modems	on the	DDD
	     telephone	network	 is not	1200 baud.  Combinations of
	     phase and/or amplitude modulation can be  employed	 to
	     send data at 1200 bps using a signaling rate of 300 or
	     600 baud.1	Here, the information rate (bps) >  signal-
	     ing rate (baud).

	 d.  If	you still need convincing that bps  !=	baud,  then
	     examine  the timing diagram of the	7.42 unit code used
	     by	Teletype 33 and	 43  teleprinters.   The  stop	and
	     start  pulses are of different lengths.  In this case,
	     the information rate (bps)	< signaling rate (baud).


       __________

	1. I won't present the details of any one particular model
	   modem.  This	is the kind of information that	companies
	   like	to classify as proprietary.




-- 
============================================================================
Robert S. Parnass, AT&T Bell Laboratories, ihnp4!ihuxf!parnass (312)979-5760