47 CFR § 74.463
Modulation requirements
February 16, 2021
(a) Each new remote pickup broadcast station authorized to operate with a power output in excess of 3 watts shall be equipped with a device which will automatically prevent modulation in excess of the limits set forth in this subpart.
(b) If amplitude modulation is employed, modulation shall not exceed 100 percent on negative peaks.
(c) If frequency modulation is employed, emission shall conform to the requirements specified in §74.462.
[41 FR 29686, July 19, 1976, as amended at 47 FR 54448, Dec. 3, 1982]