In a geographic area with limited satellite coverage, multiple signal sources are statically disposed along a path through the geographic area. To automatically determine geographic positions of the signal sources, signal data collected by a receiver moving along the path is received, where the signal data indicates changes, over a period of time, in strength of respective signals emitted by the signal sources. Indications of a first position of the receiver at a first time prior to entering the geographic area and a second position of the receiver at a second time subsequent to leaving the geographic area are received, and positions for the signal sources are determined using the received signal data and the received indications of the positions and the times. The determined positions for the signal sources are used to geoposition a device moving along the path.