Amateur Extra › E1 Commission Rules › E1C09
E1C09
What is the highest modulation index permitted at the highest modulation frequency for angle modulation below 29.0 MHz?
Pick an answer to check it.
Answer: B. 1.0
For FM or PM (angle modulation) below 29.0 MHz, the modulation index may be no more than 1.0 at the highest modulation frequency. This keeps HF FM signals narrow.
Tip: Below 29 MHz FM: index 1.0.
FCC rule reference: Part 97.307