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FM Signal Bandwidth

October 5th Fact-of-the-Day

The bandwidth of a frequency modulated signal can be calculated using Bessel functions. Bessel functions show that the bandwidth of an FM signal with any amount of frequency deviation is infinite. However, they also show that the amplitudes of spectral frequencies beyond the limits of frequency deviation drop off so rapidly that for most practical purposes they can be neglected. Signals included within the frequency deviation spectrum are called first-order sidebands. FM transmitters and receivers must have bandwidths sufficient to pass at least first-order sidebands or intelligence cannot be faithfully communicated. ©2004 Martek International All rights reserved.

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