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In modulation, one signal is imposed on another. Which of the following best describes this process?

1. A low-frequency audio signal is superposed on a high-frequency carrier wave
2. A low-frequency radio signal is superposed on a low-frequency audio wave
3. A high-frequency audio signal is superposed on a low-frequency radio wave
4. A low-frequency audio signal is superposed on a low-frequency radio wave

Correct answer: A low-frequency audio signal is superposed on a high-frequency carrier wave

Solution

Modulation superposes a low-frequency audio (message) signal onto a high-frequency carrier wave for transmission.

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