Methods and apparatuses which use satellite position system (SPS) reference receivers. In one example of the invention, a plurality of SPS reference receivers, such as Global Positioning System (GPS) reference receivers, each having a known position, are dispersed over a geographical region. Each of the SPS reference receivers transmits into a communication network, a representation of at least a portion of a satellite navigation message, such as satellite ephemeris data, received from SPS satellites in view of the particular SPS reference receiver. A plurality of digital processing systems, such as a first and a second digital processing systems, are coupled to the communication network to receive the satellite ephemeris data which is transmitted through the communication network. The first digital processing system receives a first pseudorange data from a first SPS mobile receiver and calculates a first position information of the first SPS mobile receiver from a representation of the first pseudorange data and from satellite ephemeris data received from the communication network. The first digital processing system may also receive pseudorange corrections from the communication network and use these corrections to correct the first pseudorange data to provide the representation of the first pseudorange data. The second digital processing system receives a second pseudorange data from a second SPS mobile receiver and calculates a second position of the second SPS mobile receiver using the second pseudorange data (which may be corrected using pseudorange corrections from the communication network) and using satellite ephemeris data received from the communication network. In one embodiment of this example of the invention, the mobile SPS receivers are communicatively coupled with the digital processing systems in part through a wireless cell based communication system. A further digital processing system may also be coupled to the communication network to receive pseudorange correction data and to provide merged pseudorange correction data to the digital processing systems through the communication network.