Cork Institute of Technology
Bachelor of Engineering (Honours) in Electronic Engineering – Award
(Bachelor of Engineering in Electronic Engineering – Award)
(NFQ – Level 8)
Summer 2005
Elective: Applied Digital Signal Processing
(Time: 2 Hours)
Answer any four questions [each 25
marks]
Maximum available mark is 100.
Examiners: Dr. Joseph Connell
Prof. Cyril Burkley
Mr. John Ryan
Q1. (a) A Dual-Tone, Multi-Frequency signal consisting of a 770Hz and a 1336Hz
component is sampled at 8kHz. Discuss an analysis procedure for accurately
determining the spectral content of the digital signal. Assume that 40mSecs
maximum of data is available. [10 marks]
(b) A 30Hz, unity amplitude sinwave is sampled at 80Hz. Use a Goertzel cell to
evaluate the DFT at the frequency of interest. [15 marks]
Q2. (a) Compare the Periodogram and Bartlett methods for calculating the power
spectrum of a digital signal. [10 marks]
(b) The causal impulse response of an LTI system is given as
=
)(nh {2 -4 3}.
The causal input is given as
=
)(nx {6 -1}. Show that )(*)()( lrlhlr xxyx
=
.
Indicate how this expression might be used in system identification. [15 marks]
Q3. (a) A file contains digital data sampled at s
f Hz. Describe in detail using
amplitude plots the spectral implications of inserting I zeros between each
sample. [10 marks]
(b) A signal of bandwidth 5.70
≤
≤fkHz is sampled at 20kHz. It is required to
generate a second sequence of samples corresponding to a sampling frequency
of 15kHz. Discuss a strategy for producing the second sequence. Write
efficient software to perform the interpolation task. Assume any filter used is
4th order. [15 marks]
