dillon@HERMES.BERKELEY.EDU (Matt Dillon) (07/07/89)
:The term "baud" DOES mean "bits per second", not "characters per second". :We use it just like we use "herz" as a synonym for "cycles per second". : :The person who reported that "baud" means "characters per second" is simply :wrong. : :As a laboratory demonstration, I have a 2400 baud modem, and I run DNET. :(Great stuff, Matt!) For those of you who do not know, DNET uses the line fully :during downloads - no pauses waiting for acknowledgements. WHen downloading I :get about 10K per minute transfer rate. (And, as the old joke goes, I'm :THANKFUL for it. Just wait'll I have kids and they complain about how slow :their T1 line is.) : :10240 bytes per 60 seconds = 171 bytes per second : = 1710 bits per second : :The rest is DNET's blocking and protocol and escaping. I'm not getting anything :like 2400 BYTES per second. Well, actually, the term BPS means 'bits per second'. Baud means 'tokens per second' or 'state changes per second'. For example, a 2400 BPS modem actually runs at 600 baud (or is it 1200? I forget). Each state change represents 4 bits (16 possible phases of the carrier). Slower modems... 600 BPS on down use FSK (frequency shift keying) and BAUD == BPS in this case... each FSK state change represents a single bit. I forgot what 1200 BPS modems used. Since up till a couple of years ago the majority of modems have been 600 BPS or lower most people began applying the neato term 'baud' to everything. Including me... Just a bit of mangled history, -Matt
rodd@dasys1.UUCP (Rod Dorman) (07/13/89)
> For example, >a 2400 BPS modem actually runs at 600 baud (or is it 1200? I forget). >Each state change represents 4 bits (16 possible phases of the carrier). 16 level Quadrature Amplitude Modulation at 600 baud >I forgot what 1200 BPS modems used. 4 level Phase Shift Keying at 600 baud -- Rod -- Rod Dorman rodd@dasys1.uucp Big Electric Cat Public Unix "The ships hung in the sky in much the same way that bricks don't"