Which modulation technique varies the duration of a fixed-width pulse to encode information?

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Multiple Choice

Which modulation technique varies the duration of a fixed-width pulse to encode information?

Encoding information by changing how long a pulse stays high within a fixed period is pulse-width modulation. In PWM, the pulse amplitude and the time between pulses stay the same, but the width of each high pulse varies. This changes the duty cycle, which is the fraction of time the signal is high, and that varying duty cycle carries the data. Amplitude modulation would change the peak height of the signal, not the pulse width. Frequency modulation would change how often the pulses occur, not how long each pulse lasts. Pulse-height modulation would change the pulse height, not the duration.

Encoding information by changing how long a pulse stays high within a fixed period is pulse-width modulation. In PWM, the pulse amplitude and the time between pulses stay the same, but the width of each high pulse varies. This changes the duty cycle, which is the fraction of time the signal is high, and that varying duty cycle carries the data.

Amplitude modulation would change the peak height of the signal, not the pulse width. Frequency modulation would change how often the pulses occur, not how long each pulse lasts. Pulse-height modulation would change the pulse height, not the duration.

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