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Unformatted text preview: 2-1YEDITEPE UNIVERSITY ENGINEERING FACULTY COMMUNICATION SYSTEMS LABORATORY EE 351 – COMMUNICATION SYSTEMS I EXPERIMENT 2: ENVELOPES & ENVELOPE RECOVERYObjective: Examining and recovering envelopes of AM modulated signals. Equipment: ¾Multiplier Module ¾Audio Oscillator Module ¾Master Signals Module ¾Scope Selector Module ¾Variable DC Supply Module ¾Adder Module ¾Utilities Module ¾Tunable LPF Module ¾60kHz LPF Module ¾Oscilloscope General Information: The envelopeof a signal is that boundary within which the signal is contained, when viewed in the time domain. It is an imaginary line.This boundary has an upper and lower part and these parts are mirror images of each other. It is customary to consider only one of them as ‘the envelope’ (typically the upper boundary). It is possible to generate a signal having the same shape as this imaginary line. The circuit which does this is commonly called an envelope detector. Every signal has an envelope. For a narrow band signal () ())(cos).(tttatyoϕω+=, the envelope signal is e(t) = ⎪a(t)⎪. When considering DSB signals, ( ))cos.1.(tmAtemω+=. For the case m ≤1, the absolute sign has no effect, and so there is a linear relationship between the message and the...
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This note was uploaded on 10/18/2009 for the course EE ee353 taught by Professor Ee during the Spring '05 term at Istanbul Technical University.
- Spring '05