Optimal Post Correlator Diversity Reception with Beamforming for the Ship Relative Global Positioning System (SRGPS)

"In the SRGPS landing system, phase observables are uplinked to approaching aircraft where an integer ambiguity based double difference solution is computed. The probability of successful updates is sensitive to the number and quality of carrier phaseobservables. SRGPS must contend with rapidly changing multipath scatter and blockages from the ship's structure. Antenna mounting limitations mandate multiple antenna diversity: System software must continuously select the best available signal path foreach satellite. A post correlator diversity (PCD) approach has been developed for monitoring and weighting raw data prior to tracking loops by leveraging TISI's patented Integrated Demodulation/Navigation (IDN) processor. In contrast to conventional postloop diversity (PLD), this method responds before tracking loop damage can occur. PCD also offers J/S improvement.Phase biases induced by antenna lever errors are minimized by integrating ship flexure and IMU biases states. Beamformer diversity antenna elements are utilized for enhanced jamming margin and multipath rejection. Beamformer synthesis is based upon aproven military design. Integrity monitoring is provided over an independent ship-referenced path. In TISI's Phase I effort, both non-linear tracking simulations of the SRGPS shipside architecture and interfaces between TISI's PCD processor and RockwellCollins beamformer are carried out. The post correlator diversity process