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(ELEC360)quiz01sol.pdf
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Hong Kong University of Science & Technology
Department of Electrical & Electronic Engineering

Fall 2001 ELEC 360: Digital Media & Multimedia Applications Mansun Chan
Name: ________________________ E-mail: ___________________________ ID: ________________________
Quiz #1 (Solution)
1. In human speech, the highest frequency of interest is only about 4.5kHz. What is the minimum sampling rate you should use to completely reproduce of the sound?
9KHz
2. If the frequency of middle C in piano is 261Hz, what is the frequency of its second octave given below.

First octave
1044Hz
3. For the given 8x8 bitmap gray scale image (already centered at 0), what is the DC component after the DCT process?
5.5 x 8 = 44
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
10 10 10 10 10 10 10 10
10 10 10 10 10 10 10 10
10 10 10 10 10 10 10 10
10 10 10 10 10 10 10 10

4. Name one audio effect for each of the following category:
(a)
time delay: e.g. echo

(b)
signal amplitude: e.g. Panning


5. What is the advantage of Differential Pulse Code Modulation (DPCM) over normal PCM representation?
Smaller number of bits per sample is required to store the data for highly correlated signals (Note that the statement may not be correct for purely random signal like noise)