Probability in Electrical Engineering
A signal is a physical quantity that varyies with time. The physical quantity is converted into the electrical form by means of some transducers . For example, the time-varying electrical voltage that is generated when one speaks through a telephone is a signal. More generally, a signal is a stream of information representing anything from stock prices to the weather data from a remote-sensing satellite.
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Figure 1 A sample of a speech signal
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