Extra exam question E1C09
Subelement E1, COMMISSION RULES· Group E1C · 47 CFR §97.307
What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?
- A.0.5
- B.1.0 (correct answer)
- C.2.0
- D.3.0
WhyThe highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz is 1.0. §97.307 limits the modulation index for angle modulation (FM and phase modulation) below 29.0 MHz to 1.0 at the highest modulation frequency, keeping the resulting bandwidth narrow enough to fit HF channel spacing, answer B. A modulation index of 0.5 is more restrictive than required, and 2.0 or 3.0 would produce more sidebands and more bandwidth than the rule allows on these lower frequencies.
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.
Related questions
- E1C01What is the maximum bandwidth for a data emission on 60 meters?
- E1C02Which of the following apply to communications transmitted to amateur stations in foreign countries?
- E1C03How long must an operator wait after filing a notification with the Utilities Technology Council (UTC) before operating on the 2200-meter or 630-meter band?
- E1C04What is an IARP?
- E1C05Under what situation may a station transmit third party communications while being automatically controlled?