This is a helper site for Longley Rice propagation calculations on the Misc Tools site.

Go to Misc, propagation for a choice of propagation models.

Instructions for the Propagation Mapper

Mapper is a Geo Location site meant to assist in the propagation analysis of broadcast transmitters and radio links. The propagation or ground coverage is calculated using the Longley Rice model from the geolocation (latitude-longitude) information of the transmitter and receiver.

To start with the the location of the transmitter is to be found, then if a radio link is desired the receiver location entered.

Given two points we find the terrain profile between the ends. Thus if the transmitter is to be on high terrain, different sites can be terrain profile analysed for the best coverage.

NOTE: For BEST results and accuracy of placement a 4K monitor should be used. (Min resolution: 3840 x 2160). Lower resolution will give inaccurate placement ( eg: a 620 x 480 will have a 1Km accuracy placement)

Notes on Map types

It should be noted that two different map types are employed, degree linear and distance linear.

The UK maps are distance linear, degree distorted. That is each map is linear in each direction so the radiation profile used broadcast analysis will always be circular.

Whereas for rest of the world the maps are degree linear distance distorted. This means the actul coverage of a map is constant and linear in degrees. The actual coverage in distance is highly dependent on the latitude and longitude. Only at the equator will the maps be linear square. Hence the broadcast radiation maps will appear as ellipse, elongated east to west. At the equator these ellipse will tend to a circle.


Having entered the latitude-longitude or selected a predefined location, we go to the general map. This is a large scale vision of the area. We can move around the compass points, looking for a site with transport access. The general map centres on the location and the information is for the current crosshair position and the terrain height.

Click on a map position will bring up the location parameters and height of the red-cross. The map can be re-centralised at this position or an alternative position clicked.

If the zoom level is sufficiently high a detail mode become available. Click the detail button for this. The detail mode behaves in the same way as the general mode, except it is not possible to move the map except by re-centralisation. Again two point can be selected and the intersite terrain profile calculated.

There is a third mode of operation, the terrain mode. This is a colour shaded height map. In this way the high points coverage shadows can easily be seen.