Abstract: A method for enhancing GPS location accuracy includes providing a base station receiver having a known surveyed location, and a roving receiver at a location distinct from the base station receiver. The method further includes receiving single-frequency code and carrier-phase measurements from the base station, and translating the single-frequency code and carrier-phase measurements to a Kalman filter-predicted location of the roving receiver. The translated single frequency code and carrier phase measurements are used to generate a local replica of the Kalman filter-predicted location signals for each channel of the roving receiver. The method further includes correlating the local replicas with an incoming signal of the roving receiver to generate a plurality of tracking error estimates. The plurality of tracking error estimates are used to update navigation states and clock update states thereof.

Abstract: A method and apparatus is provided for intra-PIT signal decomposition of a signal received with RF front end hardware. The method begins by aligning a signal received by RF front end hardware into integer multiples of a duration of a pseudorandom noise code sequence. A search grid is computed based on an integer multiple of the aligned signal. A plurality of initial ray parameters associated with the computed search grid is coarsely estimated. Using the coarsely estimated plurality of initial ray parameters, a fine estimation of the plurality of initial ray parameters is initiated utilizing stochastic search and optimization techniques. A stopping criteria statistic is computed by comparing a peak power of the search grid with a noise power present in the search grid. Finally, in response to determining the stopping criteria statistic being less than a stopping criteria threshold, processing a next integer multiple of the aligned signal.

Abstract: A method and apparatus is provided for intra-PIT signal decomposition of a signal received with RF front end hardware. The method begins by aligning a signal received by RF front end hardware into integer multiples of a duration of a pseudorandom noise code sequence. A search grid is computed based on an integer multiple of the aligned signal. A plurality of initial ray parameters associated with the computed search grid is coarsely estimated. Using the coarsely estimated plurality of initial ray parameters, a fine estimation of the plurality of initial ray parameters is initiated utilizing stochastic search and optimization techniques. A stopping criteria statistic is computed by comparing a peak power of the search grid with a noise power present in the search grid. Finally, in response to determining the stopping criteria statistic being less than a stopping criteria threshold, processing a next integer multiple of the aligned signal.

Abstract: A micro air vehicle having a navigation system with a single camera to determine position and attitude of the vehicle using changes the direction to the observed features. The difference between the expected directions to the observed features versus the measured direction to the observed features is used to correct a navigation solution.

Abstract: A multicarrier modulation position determination method that includes deploying at least one known receiver with a known location and a second receiver with an unknown location. At least two signals of opportunity with different locations are obtained by both the receiver and the second receiver. The signals having a plurality of block data, the block data having block boundaries. The block boundaries including a beginning block boundary and an end block boundary. The block data further including a cyclic prefix at the beginning block boundary. Acquiring a plurality of data samples for at least a portion of the block data and correlating the attained signal of opportunity between the receivers. The correlating process includes the calculation of a time difference of arrival between the known receiver and the second receiver. The time difference of arrival is calculated by aligning the block boundaries and computing a single scalar statistical feature associated with each block.