Abstract: A receiver for continuous carrier phase tracking of low carrier-to-noise ratio (“CNR”) signals from a plurality of radio navigation satellites while the receiver is mobile. The receiver may have: a radio frequency (RF) front-end that provides satellite data corresponding to signals received from the plurality of radio navigation satellites; an inertial measurement unit (IMU) that provides inertial data; and a processor circuit in circuit communication with the RF front end and the IMU, the processor circuit being capable of using satellite data from the RF front-end and inertial data from the IMU to perform continuous carrier phase tracking of low CNR radio navigation satellite signals having a CNR of about 20 dB-Hz, while the receiver is mobile. The receiver may be a GPS receiver for continuous carrier phase tracking of low-CNR GPS signals.

Abstract: A precision approach guidance system that provides flying craft guidance information during a precision approach to a landing site and methods associated therewith are provided. In one embodiment, the system includes: an inertial navigation system, an onboard ranging sensor, a terrain database storing previously identified position-referenced terrain information associated with the landing site, and a position determining process. The position determining process repetitively determines a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from an inertial navigation system, current position-referenced terrain information based on measurements from an onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database.

Abstract: A method and apparatus for constructive use of a multipath signal in GPS signal processing is provided. In one embodiment, the method includes: a) receiving a GPS signal at a mobile object from a satellite vehicle, b) determining a distance characteristic relating a reflecting object to the mobile object, c) determining at least one inertial characteristic associated with the mobile object, d) predicting at least one multipath signal characteristic associated with reflection of the GPS signal by the reflecting object toward the mobile object, and e) determining the GPS signal received in a) includes a multipath signal associated with reflection of the GPS signal by the reflecting object toward the mobile object. In one embodiment, the apparatus includes: a GPS receiver, a storage device, an inertial measurement device, and a controller. In another embodiment, the apparatus also includes a distance measurement device.

Abstract: A precision approach guidance system that provides flying craft guidance information during a precision approach to a landing site and methods associated therewith are provided. In one embodiment, the system includes: an inertial navigation system, an onboard ranging sensor, a terrain database storing previously identified position-referenced terrain information associated with the landing site, and a position determining process. The position determining process repetitively determines a corrected position of the flying craft during the precision approach based at least in part on attitude and velocity information from an inertial navigation system, current position-referenced terrain information based on measurements from an onboard ranging sensor, and previously identified position-referenced terrain information from the terrain database.