ARLA/CLUSTER: FCC propõe rever os níveis de protecção contra interferências da classe A para estações na banda de AM

[João Costa > CT1FBF]

FCC propose revised interference protection for Class A AM stations

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:

Is 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 seek 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 percent exclusion RSS
NIF level (calculated using the multiple station method).

Download the FCC proposal from
https://www.fcc.gov/document/fcc-proposes-revised-interference-protection-class-am-stations
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