Bit Rates and Baud Rates
Many people
use the terms bit rate and baud
rate interchangeably,
even though as we see with the Manchester
encoding, they are not the same thing. While the Manchester encoding is an
example of a case in which a link’s baud rate is greater than its bit rate, it
is also possible to have a bit rate that is greater than the baud rate. This would
imply that more than one bit is encoded on each pulse sent over the link.
To see how
this might happen, suppose you could transmit four distinguished signals over a
link rather than just two. On an analog link, for example, these four signals might
correspond to four different frequencies. Given four different signals, it is
possible to encode two bits of information on each signal. That is, the first
signal means 00, the second signal
means 01, and so on. Now, a sender (receiver) that is
able to transmit (detect) 1000 pulses per second would be able to send
(receive) 2000 bits of information per second. That is, it would be a
1000-baud/2000-bps link.
