US lawFederal (United States)RegulationsTitle 47 CFR — TelecommunicationChapter I — FEDERAL COMMUNICATIONS COMMISSIONPart 74 — EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICESSubpart F — Television Broadcast Auxiliary Stations74.66347 C.F.R. § 74.663Modulation limits.Last amended: 2016Year: 2026Length: 18 wordsOfficial source Cite as 47 C.F.R. § 74.663 (2026)If amplitude modulation is employed, negative modulation peaks shall not exceed 100%. [45 FR 78694, Nov. 26, 1980]Previous47 C.F.R. § 74.661Next47 C.F.R. § 74.682