Abstract: A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.

Abstract: A GPS receiver fault detection method for use in a GPS attitude determination system having Q Receivers, wherein Q>3, includes providing R attitude solutions using subsets of P Receivers and signals from two or more space vehicles, wherein 3.ltoreq.P.ltoreq.Q-1. Post-update measurement residual sets equal to the number R of attitude solutions are determined. Each of the post-update measurement residual sets corresponds to one of the attitude solutions. "S" Receiver faults are detected by comparing the R post-update measurement residual sets, wherein 1.ltoreq.S.ltoreq.Q-3. A faulty Receiver detection system for carrying out the method is also described.

Abstract: A method for use in vehicle attitude determination includes generating GPS attitude solutions for a vehicle using three or more antennas receiving GPS signals from two or more space vehicles. An inertial navigation system is initialized by setting the attitude of the inertial navigation system to a GPS attitude solution generated for the vehicle and/or the attitude of the inertial navigation system is updated using the GPS attitude solutions generated for the vehicle or GPS estimated attitude error generated for the vehicle. A system for use in vehicle navigation is also provided.

Abstract: A multipath detection method for use in a GPS position determination system includes providing a code pseudorange measurement representative of a range of an antenna to a space vehicle and a carrier phase pseudorange measurement representative of the range of the antenna to the space vehicle. A code-carrier measurement difference is then generated between the code pseudorange measurement and the carrier phase pseudorange measurement. This code-carrier measurement difference is examined to determine if a multipath component is present. If, the difference indicates that multipath is likely to be present, use of such measurements in computing position solutions, such as attitude solutions, is avoided. A multipath detection system for carrying out the method is also described.