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Subelement H: Modulation— Topic 59: Pulse Modulation

Question 3-59H6

Element 3 (GROL)

What is one way that voice is transmitted in a pulse-width modulation system?

Explanation
In Pulse-Width Modulation (PWM), the instantaneous amplitude of the modulating signal, such as a voice waveform, directly controls the *duration* (or width) of a series of pulses. A louder (higher amplitude) portion of the voice signal will cause the generated pulse to be wider, while a quieter (lower amplitude) portion will result in a narrower pulse. This varying pulse duration then carries the voice information for transmission. Option A describes Pulse-Amplitude Modulation (PAM), where the pulse's amplitude is varied. Option B describes Pulse-Position Modulation (PPM), where the pulse's timing or position is varied. Option D describes Pulse-Frequency Modulation (PFM), where the number of pulses per second (frequency) varies.

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