Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005)

Abstract

Cross correlations caused by the limited dynamic range of the GPS Gold codes represent a significant problem in the observation of weak GPS signals. This is of particular concern in applications such as assisted GPS for E911 and in the use of GPS for remote sensing where the presence of a single strong GPS signal can make observation of other weaker signals difficult. A number of different techniques have been developed to deal with the ‘near-far’ problem ranging from cancellation (subtraction) methods through to subspace-projection techniques. This paper provides a brief review of the cross correlation problem followed by a description of a new a sub-optimal approach to dealing with the ‘near-far’ problem. The new technique is similar in approach to the subspace projection techniques already described in the literature, but is realizable in hardware or software, thereby making the method applicable for real receivers. Simulations showing the performance of the method under various scenarios are given and the advantages and limitations of the technique are discussed