ARRL Technician Practice Exam

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Prepare for the ARRL Technician Exam with detailed quizzes, flashcards, and explanations to boost your understanding and ensure success!

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What determines the amount of deviation of an FM (as opposed to PM) signal?

The frequency of the carrier signal
The amplitude of the modulating signal
The length of the transmission line
The type of antenna used

The correct answer is: The amplitude of the modulating signal

The amount of deviation of an FM (Frequency Modulation) signal is determined by the amplitude of the modulating signal. In FM, the frequency of the carrier wave is altered in accordance with the instantaneous amplitude of the modulating audio or information signal. This means that the greater the amplitude of the audio signal, the greater the deviation of the carrier frequency from its center frequency. This relationship is critical in FM transmission as it affects how much the frequency shifts in response to the modulating signal. Higher amplitude in the modulating signal results in a larger frequency variation, which is what creates the information-carrying characteristics of FM radio. The other options, such as the frequency of the carrier signal, the length of the transmission line, and the type of antenna used, do play roles in the overall transmission system, but they do not directly influence the amount of deviation in an FM signal. The carrier frequency itself is fixed during the modulation process, while the transmission line and antenna primarily affect the quality and range of the signal rather than the modulation characteristics.