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Unformatted text preview: University of Toronto ECE316 Fall 2011 Communicaon Systems September 9, 2011 L N #1 Instructor: Ivo Maljevi 1 Communicaon System A block diagram of a typical communicaon system is shown in Figure 1. The details of any specic communicaon systems dier, but the most important (common) funconal blocks are present in this block diagram. The source and the desnaon are the end points in the communicaon system chain. When the data generated by the source are non-electric, an input transducer converts them into an electrical signal(also known as the message signal), while an output transducer performs the opposite operaon. Figure 1: Communicaon system block diagram Message signal (point "A") carries the informaon intended for the desnaon/user. Transmier converts the message signal into a transmied signal (point "B"). This new signal is beer suited for transmission over the channel. Channel is the transmission media between the transmier and receiver (e.g., air for radio waves, cables for wired communicaons, etc.) As the signal travels through the channel, it gets distorted. Also, noise and interference are added to the signal, making the process of signal recovery more dicult. Receiver recovers the message signal from the received signal (point "C") up to a degree; that is why we call the recovered signal (point "D") an esmate of the message signal (point "A"). The purpose of communicaon systems is to carry informaon from the point of origin (source) to its desnaon. The ow of informaon can be in one direcon, in which case we have a broadcast system , or in two direcons, which is known as point-to-point communicaon. 1.1 Outline Some of the most important yet very basic mathemacal tools for the me domain analysis of the electrical signals used in communicaon systems (energy/power, vector representaon, classicaon, Fourier series expansion, etc.) will be introduced in Chapter 2 ....
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