Subject Code Credit: Digital Communication UEC 607 4
Subject Code Credit: Digital Communication UEC 607 4
Subject Code Credit: Digital Communication UEC 607 4
In M-ary PSK, the phase of the carrier takes on one of the M possible
values i.e. θi=2iπ/M, i=0,1,……………M-1.
2E 2i
si (t ) Cos 2f ct i 0,1,2,......... .......... ...., M 1
T M
where i= 0, 1, 2…M-1
Coherent M-ary PSK Receiver
The optimum receiver for coherent M-ary PSK includes a pair of
correlators with reference signals in phase quadrature.
The two correlators output are fed to the phase discriminator that first
computes the phase estimate.
−1
𝑥𝑄
𝜃= tan
𝑥𝐼
M-ary QAM
where A=
a) Quadrature component
b) in-phase component
M-ary QAM
• The general form of M-ary QAM is defined by the transmitted
signal
and
where L = sqrt(M)
For 16-QAM
We have:
Basis Functions
The signal si(t) can be expanded in terms of a pair of basis functions
M-ary QAM Transmitter
M –ary QAM - Receiver
M-ary FSK
Continued…
Comparison of Power bandwidth Requirement