METHODS AND APPARATUS FOR DETECTING GNSS SATELLITE SIGNALS IN SIGNAL DEGRADED ENVIRONMENTS

摘要

A location determining device and method of detecting GNSS signals, the method includes: determining candidate GNSS satellites orbiting above the location determining device using an estimated location area, time and predicted orbit data of all GNSS satellites and for the candidate GNSS satellites, determining nominal Dopplers by projecting velocities of the candidate GNSS satellites onto the estimated location area; determining correlation search spaces around the respective nominal Dopplers over estimated code phases; determining correlators for the correlation search spaces and performing correlation; determining receiver clock bias when correlation peaks associated with a majority of GNSS satellites are located at a common Doppler offset; detecting GNSS signals within the common Doppler offset using a set of detectors, one of the set of detectors detecting a correlation peak having a highest probability of detection; and determining a reduced search space in which GNSS signals may be detected.