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Unformatted text preview: ECE501 Introduction to Analog and Digital Communications Autumn 2008 Homework #3 Oct. 10, 2008 HOMEWORK ASSIGNMENT #3 Due Mon. Oct. 20, 2008 (in class) Reading: 1. Ch. 3.6–3.8. 2. Ch. 4, sections 1, 2, 6, 8 3. Midterm #1: Friday, October 24. Problems: 1. Coherent QAM Computer Experiment : (a) Repeat 4(a) from HW #2 to generate two message signals, m I ( t ) and m Q ( t ) (but without plots). Then simultaneously QAMmodulate the messages using carrier frequency f c = 200 Hz. Plot the transmitted signal in time and frequency domains using plottf . Does the transmitted signal look as expected? Comment on the frequencydomain symmetry. (b) Coherently QAMdemodulate the transmitted signal using the same LPF designed in HW #2.4(c), then superimpose plots of the recovered and original message signals (using the method of problem HW #2.4(c)). How do the recovered signals compare to the original messages? (c) Repeat part 2.4(c) assuming the receiver has a carrier phase offset of π/ 2 radians, and com ment on the effect. 2. Say that a friend of yours proposed to modulate message m ( t ) with singlesided bandwidth W Hz as follows: s ( t ) = [ m ( t ) + A ] sin(2 πf c t ) , where f c W....
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This note was uploaded on 10/25/2009 for the course ECE 501 taught by Professor Schniter,p during the Spring '08 term at Ohio State.
 Spring '08
 Schniter,P

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