Coverage map

Coverage maps are designed to indicate the service areas of radiocommunication transmitting stations. Typically these may be produced for radio or television stations, for mobile telephone networks and for satellite networks. Such maps are alternatively known as propagation maps. For satellite networks, a coverage map is often known as a footprint.

Typically a coverage map will indicate the area within which the user can expect to obtain good reception of the service in question using standard equipment under normal operating conditions. Additionally, the map may also separately denote supplementary service areas where good reception may be obtained but other stations may be stronger, or where reception may variable but the service may still be usable.

The field strength that the marked service boundary on a coverage map represents will be defined by whoever produces the map, but typical examples are as follows:

For VHF(FM) / Band II, the BBC defines the service area boundary for stereo services as corresponding to an average field strength of 54 dB (relative to 1 µV/m) at a height of 10 m above ground level. For mono it is 48 dB (relative to 1 µV/m).

The receiving antenna height of 10m dates from the 1950s when receivers were relatively insensitive and used rooftop antennas. Although this may seem unrealistic for typical situations today, when combined with the above threshold it is considered a good proxy for providing coverage to more sensitive modern receivers used without external rooftop antennas.

For MF / Mediumwave, the BBC defines the daytime service area boundary as a minimum field strength of 2 mV/m. At night, the service area of mediumwave services can be drastically reduced by co-channel interference from distant stations.

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