Signal processing techniques for improving the sensitivity of GPS receivers

A system for measuring the pseudo range from a target GPS sensor to a designated navigational satellite, for use in a satellite positioning system (SPS) is comprised of multiple GPS sensors for receiving and recording portions of the signals transmitted by designated navigational satellites, the recordings referred to as datagrams; and means for transmitting the datagrams to a datagram processing facility wherein the pseudo range from the target GPS sensor to the designated navigational satellite is derived. The datagram processing facility for deriving the pseudo range is further comprised of a pseudo range engine for deriving a pseudo range from a datagram originating with said target GPS sensor, the location of which is to be determined, the derivation accomplished with the aid of a perfect reference; a perfect reference engine for generating a perfect reference from one or more satellite-specific datagrams: and a strong signal suppression engine for synthesizing satellite-specific datagrams from I/F signals recorded by reference GPS sensors designated for the express purpose of perfect reference generation. The perfect reference reduces the minimum signal strength required to acquire and accurately track GPS satellites at or near the horizon.