Service contour
Encyclopedia
In US broadcasting
, service contour (or protected contour) refers to the area in which the Federal Communications Commission
(FCC) predicts and allows coverage.
The FCC calculates FM
and TV
contours based on effective radiated power
(ERP) in a given direction, the radial height above average terrain
(HAAT) in a given direction, the FCC's propagation curveshttp://www.fcc.gov/mb/audio/bickel/curves.html, and the station's class. AM
contours are based on the standard ground wave
field strength pattern, the frequency
, and the ground conductivity
in the area. While the FCC makes FM and TV service contour data available, there is no AM
data published by the FCC (as of January 2007).
Broadcasting
Broadcasting is the distribution of audio and video content to a dispersed audience via any audio visual medium. Receiving parties may include the general public or a relatively large subset of thereof...
, service contour (or protected contour) refers to the area in which the Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) predicts and allows coverage.
The FCC calculates FM
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
and TV
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
contours based on effective radiated power
Effective radiated power
In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of radio frequency energy using the SI unit watts, and is determined by subtracting system losses and adding system gains...
(ERP) in a given direction, the radial height above average terrain
Height above average terrain
Height above average terrain is used extensively in FM radio and television, as it is actually much more important than effective radiated power in determining the range of broadcasts...
(HAAT) in a given direction, the FCC's propagation curveshttp://www.fcc.gov/mb/audio/bickel/curves.html, and the station's class. AM
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
contours are based on the standard ground wave
Surface wave
In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...
field strength pattern, the frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
, and the ground conductivity
Ground conductivity
Ground conductivity refers to the electrical conductivity of the subsurface of the earth.-Radio propagation:Ground conductivity is an extremely important factor in determining the field strength and propagation of surface wave radio transmissions...
in the area. While the FCC makes FM and TV service contour data available, there is no AM
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
data published by the FCC (as of January 2007).