From: John Mc Donald (John.McDonald at domain may.ie)
Date: Tue 29 Feb 2000 - 09:58:46 GMT
John Allen wrote:
> Surely its impossible for the baud rate to be lower than the bps rate?
> If baud is a measure of the number of signal changes per second,
> how is it possible to send a bit without changing the signal,
> whether FM, or AM?
Isn't possible to have a number of levels that you can change between.
More specifically, it is done through the use of constellation patterns, or
using a combination of modulation schemes e.g both phase and amplitude
modulation. For example Quadrature Amplitude Modulation (QAM) uses
sixteen possible combinations of phases and amplitudes to achieve 9600bps
on a 2400baud line.
See Tanenbaum's Computer Networks for the definitive guide.
-- ================================== John Mc Donald, Dept. of Computer Science, National University of Ireland, Maynooth, Co. Kildare, Ireland. Email : johnmcd at domain cs.may.ie Phone : +353 -1 - 7084589 Fax : +353 -1 - 7083848 http://www.cs.may.ie/~johnmcd ==================================
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