An apparatus and method are disclosed for determining the position of a vehicle at or near the surface of the Earth using navigation signals from a satellite-based navigation system. Precise position estimates are achieved by reducing effective receiver noise. A plurality of receiver means each compute a pseudorange for each satellite. A signal optimizer then uses the pseudoranges from each receiver means to compute an optimal pseudorange for each satellite. A processor means computes a vehicle position from the optimal pseudoranges.