The maps used in Radio Mobile are a combination of files. These together make a useable data set in Radio Mobile. The files that are tied together are:

• mapfile.xxx (raster image file where xxx is the extention that belongs to the type of raster)
• mapfile.dat
• mapfile.geo
• mapfile.inf
• mapfile.kml
• mapfile.sig

Unlike vector maps such as those in the object .plt format, where the information is coded within the file, Radio Mobile needs to be told where our image map fits in the world. A separate data file with this information has to be created giving reference points in the image to geographical coördinates.

Normally two points are chosen, upper left and a point towards the lower right of the image and then these are referenced to the lat and long of these points on the image.

WinAPRS uses Decimal Degrees and a .geo file. Inside the .geo file is the filename of the map image, two reference points (x/y pixels), lat and long in decimal degrees.

UI-View32 uses Degrees, Minutes, Seconds, and an .inf file. Inside the .inf file are the geographical coordinates of the upper left and lower right corners and a title for the image map.

The .sig file holds the geocoded field strength. This file is created during a Cartesian coverage when 'Save raster data to file (SIG)' is enabled.