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Unformatted text preview: THE STATE UNIVERSITY OF NEW JERSEY RUTGERS College of Engineering Department of Electrical and Computer Engineering 332:322 Principles of Communications Systems Spring Problem Set 2 1. When Is a Carrier a Good Carrier?: Given an information signal m ( t ) you want to gen erate r ( t ) = Am ( t ) cos(2 πf c t ) (1) However, life (your professor) is unkind and you’re only allowed to use cos 3 (2 πf c t ) as your carrier signal. That is, the first stage of your transmitter block diagram with m ( t ) as the input is going to be a multiplication by cos 3 (2 πf c t ) (instead of the usual sane cos(2 πf c t ) ). (a) Assume you can build any linear time invariant (LTI) filter you’d like. Can you fil ter the output of the multiplier to obtain the desired signal? If so, what is the filter characteristic? (b) Suppose cos 2 (2 πf c t ) is the carrier. Repeat the previous part. (c) Suppose we generalize the carrier to be cos n (2 πf c t ) for n > 2 . When can you generate the desired r ( t ) using LTI filters. 2. Simple Envelope Detection: Consider the following AM signal s ( t ) = A c [1 + λ cos(2 πf m t )] cos (2 πf c t ) (2) The modulation factor is λ = 1 and f c À f m . The AM signal is applied to an ideal envelope....
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This homework help was uploaded on 04/03/2008 for the course ECE ECE332 taught by Professor Rose during the Spring '08 term at Rutgers.
 Spring '08
 Rose

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