🚀 go-pugleaf

smahn@vx.cis.umn.edu (Seokmin Ahn) writes:

>Hi! netters,

(Hi...)

>The advertisement about modems confused me about Baud rate and BPS.

>Would someone please clear up this for me ?

I hope someone will correct me where I'm misleading, but I'll take a
stab at it --

Bits per second is something most of us understand; a bit is a 1 or a
0, and eight of them make a byte, or a character.  Normal modem trans-
missions will have anywhere from 7 - 9 bits per character.  N/8/1 has
become somewhat of a standard:  No parity bit, 8 bits/character, 1 stop
bit, for a total of 9 bits transmitted for every character received.

Baud is defined as symbols per second.  Some protocols, such as QAM
(Quadriture Amplitude Modulation) make a "constellation" of symbols,
where the symbol received is somewhere on an X-Y axis.  It's not im-
portant to discuss this in detail, except to say that it may require
more than one bit/symbol, and that 2400baud modems use QAM -- it's
called the V.22 protocol.

This latter paragraph is technically correct, although I believe most
ads will say "baud" and then give you a BPS figure.  I don't think I've
ever seen an ad where what they advertise as "baud" is actually symbols
per second.

Hope this helps,

Mike Stangel
-- 
 Mike Stangel -- stangel@uiuc.edu | "I can't kill the man I love."   
 Chairman		          | "Then kill the one you're with." 
 ACM at UIUC	                  |                   -Crow, MST3k   
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