Cork Institute of Technology
Bachelor of Engineering (Honours) in Electronic Engineering – Award
(Bachelor of Engineering in Electronic Engineering – Award)
(NFQ – Level 8)
Autumn 2005
APPLIED DIGITAL SIGNAL PROCESSING
(Time: 2 Hours)
Answer any four questions [each 25
marks]
Maximum available mark is 100.
Examiners: Dr. J. Connell
Prof. C. Burkley
Mr. J. Ryan
Q1. (a) A unity-amplitude, 15Hz sin wave is sampled at 90Hz. 8 samples are taken
from the sequence for spectral analysis. Discuss the nature of the amplitude
spectrum thus produced. Include in your discussion possible window options
and their effects. [10 marks]
(b) Using a Goertzel cell and one period of samples, evaluate the DFT for the
signal in (a) at the frequency of interest. [15 marks]
Q2. (a) Discuss the nature and use of correlation functions in signal analysis. [10 marks]
(b) The causal impulse response of an LTI system is given as
=
)(nh {1 -3}. The
causal input is given as
=
)(nx {2 -7}. Show that )(*)()( lrlrlr hhxxyy
=
.
How is the autocorrelation function related to the power spectrum ? [15 marks]
Q3. (a) File1 contains digital data sampled at s
f Hz. Describe in detail using
amplitude plots the spectral implications of creating a new file2 using every
4th sample from file1. [10 marks]
(b) A signal of bandwidth 5.70
≤
≤fkHz is sampled at 30kHz. It is required to
generate a second sequence of samples corresponding to a sampling frequency
of 10kHz. Discuss a strategy for producing the second sequence. Write
efficient software to perform the task. Assume any filter used is 4th order. [15 marks]
