Abstract: The subject matter described herein includes methods and systems for performing physical measurements using radio frequency (RF) signals. According to one embodiment of the present invention, a method is disclosed for determining the distance between a first radio device and a second radio device. The method includes transmitting a radio frequency (RF) signal from the first radio device and receiving the RF signal by the second radio device. The method further includes a determining a carrier frequency of the RF signal and determining a slope of a carrier phase versus the carrier frequency corresponding to a rate of change of the carrier phase with the carrier frequency. The method also includes determining a physical distance between the first radio device and the second radio device based on the slope; wherein the physical distance is proportional to the slope plus an integer ambiguity term and a bias term.

Abstract: The subject matter described herein includes methods and systems for performing physical measurements using radio frequency (RF) signals. According to one embodiment of the present invention, a method is disclosed for determining the distance between a first radio device and a second radio device. The method includes transmitting a radio frequency (RF) signal from the first radio device and receiving the RF signal by the second radio device. The method further includes a determining a carrier frequency of the RF signal and determining a slope of a carrier phase versus the carrier frequency corresponding to a rate of change of the carrier phase with the carrier frequency. The method also includes determining a physical distance between the first radio device and the second radio device based on the slope; wherein the physical distance is proportional to the slope plus an integer ambiguity term and a bias term.

Abstract: A method for processing data in an inertial navigation system having a Kalman filter and computer-readable storage medium containing instructions to configure a processor to perform the same. The method produces more accurate estimates of the position, velocity and attitude of the inertial measurement unit. The method is fully automatic and enables zero-velocity updates and fixed-azimuth updates to be performed simultaneously. The method may also include a multi-stage filtering process to filter digital compass data when used in an environment with extraterrestrial magnetic field sources. The method may also include a fixed-lag smoother to improve estimates of the position, velocity and attitude of the inertial measurement unit. The method also may include processes to constrain altitude errors.

Abstract: A method for processing data in an inertial navigation system having a Kalman filter and computer-readable storage medium containing instructions to configure a processor to perform the same. The method produces more accurate estimates of the position, velocity and attitude of the inertial measurement unit. The method is fully automatic and enables zero-velocity updates and fixed-azimuth updates to be performed simultaneously. The method may also include a multi-stage filtering process to filter digital compass data when used in an environment with extraterrestrial magnetic field sources. The method may also include a fixed-lag smoother to improve estimates of the position, velocity and attitude of the inertial measurement unit. The method also may include processes to constrain altitude errors.