Extra exam question E8B02
Subelement E8, SIGNALS AND EMISSIONS· Group E8B
How does the modulation index of a phase-modulated emission vary with RF carrier frequency?
- A.It increases as the RF carrier frequency increases
- B.It decreases as the RF carrier frequency increases
- C.It varies with the square root of the RF carrier frequency
- D.It does not depend on the RF carrier frequency (correct answer)
WhyThe modulation index of a phase-modulated emission does not depend on the RF carrier frequency. A phase-modulated emission's modulation index depends only on the modulating signal itself (specifically its amplitude, for PM), not on the RF carrier frequency the modulation is riding on, so changing the carrier frequency alone doesn't change the modulation index, answer D. It doesn't increase, decrease, or vary with the square root of carrier frequency, PM's modulation index is defined independently of what carrier frequency happens to be in use.
Published 2026-08-28 · Last updated 2026-08-28 · Question text is verbatim from the 2024-2028 NCVEC Element 4 pool (public domain); the explanation above is original writing, see our methodology.
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