Nyquist

1
Nyquists theorem D 2BLog2K Provides an
absolute maximum that cannot be achieved in
practice. Engineers have observed that a real
communication system is subject to small amount
of background interference called noise, and that
such noise makes it impossible to achieve the
theoretical maximum rate. B bandwidth (2B for
the RS-232 that uses two values of voltage
data) K Possible values of voltages D Maximum
date rate in bits per second Shannons theorem
C BLog2(1 S/N) Shannon extended Nyquists work
to specify the maximum data rate that can be
achieved over a transmission system that
introduces noise. C Is the effective limit on
the channel capacity in bits per second S
Average signal power N Average noise power B
Bandwidth