An ephemeris server performs a method that includes (a) (i) obtaining broadcast ephemeris information by accessing a source of broadcast information on a wide area communication network; (ii) extracting, from broadcast ephemeris information, orbital trajectory information of each satellite, and (iii) creating and storing in a real-time database modified orbital trajectory information for each of the satellites from the extracted orbital trajectory information; (b) at each of a plurality of designated time points, updating the modified trajectory information in the real-time database, based upon evaluation of an update criterion; and (c) providing the modified trajectory information to each of a plurality of devices, each device having a GNSS receiver capable of using the modified trajectory information to process broadcast signals of the satellites.