Abstract: A shared channel GPS (Global Positioning System) receiver for receiving a plurality of coded satellite signals. The plurality of satellite signals is transmitted by a corresponding plurality of satellites. Since these satellites are moving rapidly with respect to the receiver, Doppler shifting of the signals is exhibited. The signals are converted from analog to digital at intermediate frequency levels. The signals are then separated simultaneously into a plurality of digital signals corresponding to channel information for each transmitting satellite. One channel of the receiver sequence through a number of the satellites on a time division multiplexed basis. The channel estimates a plurality of parameter pertaining to each satellite so that re-acquisition of the satellite's transmission may be facilitated. A processor then converts these channel information signals to pseudo-range and broadcast data for navigation and time purposes.

Abstract: A method for accurately determining the position of a roving signal receiver positioned on or above the Earth's surface, relative to the position of a reference receiver whose position is known with sufficient accuracy, using ranging information, transmitted at a pair of predetermined carrier signal frequencies and received from each of n satellites (n.gtoreq.4). Pseudorange double differences are formed, between each of the two receivers and each of a first satellite and the other three satellites, using pseudorange information obtained from either one of the two signal frequencies. Phase correction information, in the form of estimates of integer lane wavelength ambiguities, is then obtained from the pseudorange double differences and from certain measurable phase differences. This products n-1 simultaneous equations that can be solved for the roving receiver position cordinates.