Extra exam question E8B04
Subelement E8, SIGNALS AND EMISSIONS· Group E8B
What is the modulation index of an FM phone signal having a maximum carrier deviation of plus or minus 6 kHz if the highest modulating frequency is 2 kHz?
- A.0.3
- B.3 (correct answer)
- C.0.6
- D.6
WhyAn FM phone signal with a maximum carrier deviation of plus or minus 6 kHz and a highest modulating frequency of 2 kHz has a modulation index of 3. Modulation index equals frequency deviation divided by the modulating frequency: 6 kHz of deviation divided by a 2 kHz modulating tone works out to a modulation index of 3, answer B. The other figures come from inverting that ratio or misapplying a scale factor to these same numbers.
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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