Testing of Ultra-Tightly-Coupled GPS Operation using a Precision GPS/Inertial Simulator

Next generation high anti-jam GPS receivers will take advantage of Ultra-Tightly-Coupled (UTC) GPS/inertial signal processing to improve their anti-jam robustness. UTC signal processing uses the inertial observations to aid the GPS receiver correlation channels and extend the period over which the coherent correlator outputs can be accumulated. For UTC tracking to operate, the residual carrier error from the inertial aiding must be maintained within a fraction of a cycle. Maintaining the carrier coherence of a GPS signal to within a few centimeters of the inertial aiding observations places some new and challenging constraints on GPS RF and inertial simulators. This paper describes the design of a high fidelity simulator suitable for GPS/inertial UTC testing that has been developed by NAVSYS.