Troposphere corrections are provided in a land based transmitter-positioning system. Troposphere delays correct ranges based on X- or ISM-band carrier ranging signals with a modulation rate of the code of at least about 30 MHz. Ground based transmitters transmit non-GPS type ranging signals, and the receivers correct for troposphere delays. Troposphere delay corrections are applied to range estimates on each iteration of an iterative position-fix algorithm. Different models of troposphere corrections in a ground based ranging system may be used.