New FCC proposals would take into account the rising noise levels in the AM broadcast band (535-1605 kHz) caused by power lines, LED and CFL lights, computers, etc
The FCC asks if there common agreement that protection of the 0.1 mV/m contour is excessive because a 0.1 mV/m signal cannot be heard under current noise conditions or are there studies to the contrary?
Is the appropriate level of protection to the 0.5 mV/m groundwave contour?
The FCC sought comment on revised proposals for amending protections to Class A AM stations, which include alternative protection standards for critical hours and nighttime hours.
The following proposals all provide Class A stations with less protection than they currently enjoy; in the case of the critical hours proposals, Alternative 1 provides Class A stations with less protection than does Alternative 2, and in the case of the nighttime protection proposals, Alternative 2 in some cases provides Class A stations with less protection than does Alternative 1:
Daytime Hours Proposal:
During daytime hours, Class A AM stations are protected to their 0.5 mV/m daytime groundwave contour, from both co-channel and first-adjacent channel stations;
Critical Hours Proposals
Alternative 1: During critical hours, Class A AM stations are afforded no protection from other AM stations, as proposed in the AMR NPRM, or
Alternative 2: During critical hours, Class A AM stations are protected to their 0.5 mV/m groundwave contour;
Nighttime Hours Proposals
Alternative 1: During nighttime hours, there may be no overlap between a Class A AM station’s 0.5 mV/m nighttime groundwave contour and any interfering AM station’s 0.025 mV/m 10 percent skywave contour (calculated using the single station method); or
Alternative 2: During nighttime hours, Class A AM stations are protected from other AM stations in the same manner as Class B AM stations are protected, that is, interference may not be increased above the greater of the 0.5 mV/m nighttime groundwave contour or the 50 per cent exclusion RSS NIF level (calculated using the multiple station method).
FCC Proposal - https://www.fcc.gov/document/fcc-proposes-revised-interference-protection-class-am-stations