the concept of modulation

A ECE301Fall2008mboutin.jpg Why?

•More efficient to transmit E&M signals at higher frequencies

•Transmitting multiple signals through the same medium using different carriers

•Transmitting through “channels” with limited passbands

•Others...

How?

•Manymethods

•Focus here for the most part on Amplitude Modulation (AM)

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Amplitude Modulatioin of a Complex Exponential Carrier

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Demodulation of Complex Exponential AM

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Sinusoidal AM

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Synchronous Demodulation (with phase error) in the Frequency DomainAgain

Demodulating signal has phase difference θw.r.t.the modulating signal

$ cos(\omega_{C}t+\theta)= \frac{1}{2}e^{j\theta}e^{j\omega_{c}t}+\frac{1}{2}e^{-j\theta}e^{-j\omega_{c}t} $

fourier ====>

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Meet a recent graduate heading to Sweden for a Postdoctorate.

Christine Berkesch