Collective detection and direct positioning using multiple GNSS satellites

Abstract

This paper describes and demonstrates an assisted GPS technique, termed "Collective Detection," for combining satellite correlograms to enable rapid acquisition and direct positioning. Correctly combining correlation values from multiple satellites reduces the required C/N0 such that satellite signals, which cannot be acquired individually, can contribute constructively to a position solution. The acquisition search is performed in a position / clock space that directly yields the navigation solution. Results from a hardware simulator and live experiments are presented. The simulations compare combinations of 11 satellites and four satellites at C/N0 levels of 40 and 20 dB-Hz. The outdoor experiments show horizontal position accuracies on the order of 50 m in open sky conditions and in a narrow courtyard environment using one millisecond of data. Collective detection and positioning is shown to be a promising approach for positioning in weak signal environments.