EE661 Modulation Theory
Spring 2011
Practice Midterm Exam #1
Problem 1.
(25 points)
Zeromean, white Gaussian noise with a PSD of
is passed through a BPF whose transfer
function is as described in the figure.
(a) Find the variance of the I and Q components
of the output bandpass noise.
(b) Are the I and Q components of the noise
independent?
Carefully justify your answer.
Problem 2.
(25 points)
The four waveforms listed below are used to form a 4ary signalling format.
,
,
,
,
,
.
(a) Find a set of orthonormal basis functions such that each waveform can be written as a linear
combination of the set of basis functions.
(b) Find the vector representation of each of the four signals and plot the signal space diagram.
Be sure to label and scale your axes appropriately.
(c) Suppose that the received signal is
for
.
Convert this signal to a
received vector and plot the vector on the signal space diagram from part (b).
Which signal
should the receiver decide in favor of?
Problem 3.
(25 points)
A binary baseband pulse position modulation format,
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This note was uploaded on 02/21/2012 for the course ECEN 661 taught by Professor Miller during the Spring '11 term at Texas A&M.
 Spring '11
 Miller

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