Longley-Rice projections show an estimate of real-world reception conditions. While not perfect, particularly in extremely rough mountainous terrain, this is the same projection the FCC uses to determine whether or not a station can exist in a given location. The only differences between the projections seen on RabbitEars and those used by the FCC are that the viewer antenna is assumed to be at 13 feet rather than the FCC standard of 30 feet, and the maps are adjusted to be more pessimistic on VHF frequencies. In particular, the maps are 5 dB more pessimistic for upper-VHF and 13 dB more pessimistic for low-VHF.
Noise-Limited Bounding Contour and Minimum Field Strength Contour
The Minimum Field Strength Contour is used to determine whether or not a station provides adequate service to its community of license. The Noise-Limited Bounding Contour shows the FCC's estimated coverage. These contours were how station coverage was determined going all the way back to the 1950's, and are still used for allotment-related purposes today.
LP/CA Protected Contour
The FCC uses a lower standard for defining the coverage of low-power and Class A television stations. This contour, similar to the Noise-Limited Bounding Contour, represents that lower standard.
The F(50,10) interfering contour is used when negotiating with the Canadian and Mexican governments for TV stations in the border regions. In particular, the US treaty with Canada states that if this contour does not cross the border, then Canadian approval is not required.
This option will show all of the Census designated places used in calculating the population covered by this transmitter. There are also two options here that allow for the removal of included places and the addition of non-included places to get a custom population count. To do so, simply input the City ID numbers, separated by commas, into the appropriate boxes.
Rural LPTV Exclusion Zone
During the 2009-2010 LPTV filing window, the FCC restricted applications for new stations to areas outside a 75-mile radius of the key city in the top 100 Nielsen DMAs. This option adds gray circles to the map showing those areas where new LPTV stations were not allowed.
This option shows or hides the RabbitEars logo and menus at the top, for cleaner printing of the map.
Entering FCC Antenna Structure Registration Numbers (ASRNs) separated by commas will allow you to add one or more additional tower site(s) to the map. Around each are two circles, one at 30 miles, and one at 30.49 miles.
Entering FCC application ID numbers separated by commas will allow you to add one or more additional station(s) to the map.
Draw a Circle
Pretty self-explanatory. This allows you to draw a circle of a given radius around a user-defined set of coordinates.