The Multisensor Optimal Smoothing Estimation Software (MOSES) is a high-order Kalman filter and smoother designed to provide precise reconstruction of aircraft and missile flight test trajectories. It uses flight-recorded data from an onboard inertial navigation unit (INU) and a phase-tracking GPS receiver. The GPS pseudorange and delta-range measurements are corrected by use of GPS data from a ground reference station. MOSES is also designed to use recorded data from ground-based systems such as cinetheodolites and tracking radars.

Under subcontract to Computer Sciences Corporation (CSC), Integrity Systems (ISI) designed and implemented the MOSES 6.0 software currently in use at the Air Force Flight Test Center at Edwards AFB. The starting point for this software was ISI's DKF Simulator program, developed previously for the Air Force Research Laboratory at Wright-Patterson AFB. ISI designed and implemented several critical modules in the MOSES Filter segment: the INU solution integration module; the INU Filter module including a variety of user-selectable INU error models; and the GPS Filter module including a variety of user-selectable GPS error models. We also designed and implemented the MOSES Smoother segment including a U-D version of the Rauch-Tung-Striebel smoothing method. Finally, we developed and implemented the MOSES Models segment including high-fidelity versions of the INU and GPS truth models. The MOSES Models segment provides a valuable capability for testing the MOSES Filter and Smoother segments with user-controllable scenarios and sensor errors.

Version 7.0 of the Multisensor Optimal Smoothing Estimation Software (MOSES) provides improved accuracy by use of phase-tracking data from a kinematic GPS (KGPS) receiver onboard the test vehicle. MOSES 7.0 is a high-order Kalman filter and smoother designed to provide very precise reconstruction of aircraft and missile flight test trajectories. It uses flight-recorded data from an onboard inertial navigation unit (INU) and a conventional GPS receiver. In one mode, the onboard pseudorange (PR) and accumulated-phase (AP) measurements are corrected by means of data from a ground reference station, also equipped with a KGPS receiver. In another mode, the onboard PR and AP measurements are differenced with those from the reference station at the same times, and processed as difference measurements so common errors are suppressed.

Under subcontract to Computer Sciences Corporation (CSC), Integrity Systems (ISI) designed and implemented the MOSES 7.0 software for use at the Air Force Flight Test Center at Edwards AFB. MOSES 7.0 represents a significant increase in trajectory reconstruction accuracy over earlier versions. ISI analyzed the kinematic GPS processing requirements, and evaluated the major sources of error and their characteristics. We defined the best set of GPS filter state variables to be implemented in the MOSES Filter models, based on both accuracy and observability criteria. Last, we identified and adapted an efficient and reliable method for integer ambiguity resolution, based on the large volume of recent literature on that subject. The resulting KGPS filter and smoother design combined with integer ambiguity resolution comprises a novel and noteworthy advance in GPS positioning technology.