The duty cycle of a signal measures the fraction of time a given transmitter is transmitting that signal. This fraction of time determines the overall power delivered by the signal. Signals with longer duty cycles carry more power. This makes the signal stronger, more reliable and easily detected by receiving equipment. Signals with longer duty cycles require less efficient receivers than do signals with shorter duty cycles.
Measure the pulse width of the transmitted signal. If you do not know it, connect the output of the signal to the input of an oscilloscope. The oscilloscope screen will show a series of pulses oscillating at the frequency of the signal. Note the width, in seconds or microseconds, of each pulse. This is the pulse width, or PW, of the signal.
Calculate the period, or "T", of the frequency, or "f," using the formula: T = 1/f. For example, if the frequency is 20 hz, then T = 1/20, with a result of 0.05 seconds.
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Determine the duty cycle, represented by "D," through the formula D = PW/T. As an example, if PW is 0.02 seconds and T is 0.05 seconds, then D = 0.02/0.05 = 0.4, or 40%.