[BC] FCC AM Rules

[Harold Hallikainen]

> On Saturday 30 January 2010 01:18 pm, Jeff Glass wrote:
>
>>  I found the rules about the protected contours and the interference to
>>  desired signal ratios, I can't find anything that specifically spells
>> out what
>>  the field intensity is supposed to be, for the Primary contour,
>> Secondary
>>  contour, and Intermittent contour. (Class A) Specific rule citing would
>> be most
>>  helpful so I can refer to them.
>
>  Not sure I've ever seen a "rule" other than the old post office contour
>  requirement for city of license, but the generally accepted contours
>  are 5, 1, and 0.5 millivolt.
>  There may be a rule, but I've never really had reason to look !
>
> --
> Cowboy

http://louise.hallikainen.org/FCC/FccRules/2010/73/182/
  (d) The groundwave signal strength required to render primary service
   is 2 mV/m for communities with populations of 2,500 or more and 0.5
   mV/m for communities with populations of less than 2,500. See § 73.184
   for curves showing distance to various groundwave field strength
   contours for different frequencies and ground conductivities, and also
   see § 73.183, "Groundwave signals."

 (g) Secondary service is provided during nighttime hours in areas where
   the skywave field strength, 50% or more of the time, is 0.5 mV/m or
   greater (0.1 mV/m in Alaska). Satisfactory secondary service to cities
   is not considered possible unless the field strength of the skywave
   signal approaches or exceeds the value of the groundwave field strength
   that is required for primary service. Secondary service is subject to
   some interference and extensive fading whereas the primary service area
   of a station is subject to no objectionable interference or fading.
   Only Class A stations are assigned on the basis of rendering secondary
   service.

   (h) Intermittent service is rendered by the groundwave and begins at
   the outer boundary of the primary service area and extends to a
   distance where the signal strength decreases to a value that is too low
   to provide any service. This may be as low as a few uV/m in certain
   areas and as high as several millivolts per meter in other areas of
   high noise level, interference from other stations, or objectionable
   fading at night. The intermittent service area may vary widely from day
   to night and generally varies over shorter intervals of time. Only
   Class A stations are protected from interference from other stations to
   the intermittent service area.

Harold

-- 
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