A Robust GPS/INS Kinematic Integrity Algorithm for Aircraft Landing

Next generation GPS receivers will take advantage of Spatial processing from a Controlled Reception Pattern Antenna (CRPA) and Ultra-Tightly-Coupled (UTC) and Tightly–Coupled GPS/inertial signal processing to improve their robustness to interference and their performance in a multipath environment. This introduces the potential for failure modes to be introduced into the GPS solution from the Spatial processor, GPS signals or Inertial Measurement Units (IMUs). For high integrity applications such as nonprecision approach or precision approach, the integrated GPS/Inertial receiver must be designed to perform fault detection and exclusion of any hazardously misleading information. This paper describes the design of a GPS/Inertial Kinematic Integrity Monitor designed to monitor and detect for errors that affect the Kinematic Carrier Phase Tracking (KCPT) solution. This has been implemented and tested in NAVSYS’ HAGR digital beam-forming receiver. Testing on the algorithm performance was performed using a high fidelity simulator designed for GPS wavefront simulation and GPS/inertial UTC testing based on NAVSYS’ Advanced GPS Hybrid Simulator (AGHS). The AGHS adopts a hybrid RF/digital design that enables precision digital control of the GPS code and carrier signals. This allows coherent signal generation for simulations involving precise phase control, such as kinematic GPS testing, wavefront simulation, or ultra-tightly-coupled GPS/inertial testing. Test results are presented in this paper showing the KCPT and Integrity Monitor performance under simulated conditions where interference sources, multipath sources and GPS/inertial failures are introduced.