Signals and Spectra 1 Properties of Signals and

Signals and Spectra 1

Properties of Signals and Noise In communication systems, the received waveform is usually categorized into the desired part containing the information and the extraneous or undesired part. The desired part is called the signal, and the undesired part is called noise.

Physically Realizable Waveforms The waveform has significant nonzero values over a composite time interval that is finite. There is no known waveform that has existed forever. The spectrum of the waveform has significant values over a composite frequency interval that is finite. All practical systems have limited bandwidth which would no allow for infinite bandwidth.

Physically Realizable Waveforms The waveform is a continuous function of time. A discontinuity in the function would require infinite bandwidth. The waveform has finite peak values. Any physical device would be destroyed before producing an infinite peak value. The waveform is a Real function. Only real waveforms have been observed in the real world.

Physically Realizable Waveforms

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