Frequency Modulation

[Jon]

If an FM signal is modulated by a single frequency sine wave, what it
the result of limiting the bandwidth? Is it increased distortion of
the demodulated signal? Theoretically, the number of sidebands is
infinite. In the real world, the bandwidth is limited so that the
higher order sidebands are greatly attenuated.
Regards,
Jon

 

[Tim Wescott]

If an FM signal is modulated by a single frequency sine wave, what it
the result of limiting the bandwidth? Is it increased distortion of
the demodulated signal? Theoretically, the number of sidebands is
infinite. In the real world, the bandwidth is limited so that the
higher order sidebands are greatly attenuated.
Regards,
Jon

The result is a signal that is both frequency and amplitude modulated.
The amount of distortion depends on the receiver technology, but in
general yes, it'll be distorted.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

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"Applied Control Theory for Embedded Systems" came out in April.
See details at http://www.wescottdesign.com/actfes/actfes.html

 

[joseph2k]

If an FM signal is modulated by a single frequency sine wave, what it
the result of limiting the bandwidth? Is it increased distortion of
the demodulated signal? Theoretically, the number of sidebands is
infinite. In the real world, the bandwidth is limited so that the
higher order sidebands are greatly attenuated.
Regards,
Jon

For D > m the effective bandwidth is approximately 2 * (D+m) where D is the
p-p deviation and m is the frequency of the modulating signal.