47 C.F.R. § 74.663 Modulation limits.
Title 47 - Telecommunication
If amplitude modulation is employed, negative modulation peaks shall not exceed 100%. [45 FR 78694, Nov. 26, 1980]
Title 47: Telecommunication
PART 74—EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES
Subpart F—Television Broadcast Auxiliary Stations
§ 74.663 Modulation limits.

