Coverage map


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.

Contents

Definition of coverage

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.

Technical details

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:

VHF(FM) / Band II

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

MF / Mediumwave

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.

Limitations

Often coverage maps show general coverage for large regions and therefore any boundary indicated should not be interpreted as a rigid limit. The quality of reception can be very different at places only short distances apart, and this phenomenon is more apparent as the transmission frequency increases. Inevitably small pockets of poor reception may exist within the main service area that cannot be shown on the map due to scale issues. Conversely, the use of sensitive equipment, high gain antennas, or simply being located on high ground can yield good signal strengths well outside the indicated area. The significance of local geographical conditions cannot be over emphasised and this was underlined by an experiment which revealed the signal reception conditions around a typical house. The site did not have the critical "line-of-sight propagation" to the transmitter. Average signal levels, taken at the same height, varied by up to 6dB, and for individual frequencies by up to 14dB. In RF reception terms these figures are huge differences.

Although carriers and broadcasters attempt to design their networks to eliminate dead zones, no network is perfect, so coverage breaks within the general coverage areas are still possible.

Often companies will construct low power satellite stations to fill in bad reception areas that become apparent once the high power transmitter's coverage map has identified where the network is deficient.

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Map — /map/, n. Walter, c1140 1209?, Welsh ecclesiastic, poet, and satirist. Also, Mapes /mayps, may peez/. * * * I Graphic representation, drawn to scale and usually on a flat surface, of features usually geographic, geologic, or geopolitical of an… …   Universalium

  • Map database management — stems from navigation units becoming more common in automotive vehicles (see Automotive navigation system). They serve to perform usual navigation functions, such as finding a route to a desired destination and guiding the driver to it or… …   Wikipedia

  • Map of the Problematique — The Map of the Problematique single cover. Single by Muse from the album Black Holes and Revelations …   Wikipedia

  • map — mappable, adj. mapper, n. /map/, n., v., mapped, mapping. n. 1. a representation, usually on a flat surface, as of the features of an area of the earth or a portion of the heavens, showing them in their respective forms, sizes, and relationships… …   Universalium

  • MAP — See modified American plan. * * * I Graphic representation, drawn to scale and usually on a flat surface, of features usually geographic, geologic, or geopolitical of an area of the Earth or of any celestial body. Globes are maps represented on… …   Universalium

  • Map-Server — Ein Web Map Service (WMS) ist eine Schnittstelle zum Abrufen von Auszügen aus Landkarten über das World Wide Web. Eine solche Schnittstelle kann allgemein auch als Web Service bezeichnet werden. Inhaltsverzeichnis 1 Die WMS Implementation… …   Deutsch Wikipedia

  • Map Server — Ein Web Map Service (WMS) ist eine Schnittstelle zum Abrufen von Auszügen aus Landkarten über das World Wide Web. Eine solche Schnittstelle kann allgemein auch als Web Service bezeichnet werden. Inhaltsverzeichnis 1 Die WMS Implementation… …   Deutsch Wikipedia

  • map index — Graphic key primarily designed to give the relationship between sheets of a series, their coverage, availability, and further information on the series. See also map …   Military dictionary

  • map/chart index — The graphic key primarily designed to give the relationship between the sheets of a series rather than coverage and availability. See map sheet …   Aviation dictionary

  • Vector Map — The Vector Map (VMAP), also called Vector Smart Map, is a vector based collection of Geographic information system (GIS) data about Earth at various levels of detail. Level 0 (low resolution) coverage is global and entirely in the public domain.… …   Wikipedia