Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Pulse-frequency modulation
open-in-new
<p>Pulse-frequency modulation (PFM) is a <a href="/facts/Modulation/aAXPjINv">modulation</a> method for representing an <a href="/facts/Analog_signal/xDbb4uB5">analog signal</a> using only two levels (1 and 0). It is analogous to <a href="/facts/Pulse-width_modulation/cqjcrYs7">pulse-width modulation</a> (PWM), in which the magnitude of an analog signal is encoded in the <a href="/facts/Duty_cycle/B2tbtXTh">duty cycle</a> of a <a href="/facts/Square_wave_(waveform)/h1cWR1KM">square wave</a>. Unlike PWM, in which the width of square pulses is varied at a constant <a href="/facts/Frequency/QUSbPaW8">frequency</a>, PFM fixes the width of square pulses while varying the <a href="/facts/Frequency/QUSbPaW8">frequency</a>. In other words, the <a href="/facts/Frequency/QUSbPaW8">frequency</a> of the pulse train is varied in accordance with the instantaneous amplitude of the modulating signal at sampling intervals. The amplitude and width of the pulses are kept constant. </p>