Abstract: The present invention relates generally to methods and apparatuses for estimating and correcting for multipath in GNSS navigation systems. According to some aspects, the invention takes advantage of situations where position and estimated position error are reasonably stable so as to detect when large multipath errors are present with confidence. After detection, the slowly varying biases from multipath or other un-modeled sources can be modeled separately from the navigation state. This makes it possible to keep the measurements in the solution without biasing the navigation state and further ignores the long-term biases for use over short-term periods with minimized pseudorange error when necessary.

Abstract: A global positioning satellite (GPS) receiver that includes a radio frequency (RF) receiver receiving a first GPS signal from a GPS satellite and a processor. The processor is configured to correlate the first GPS signal with a plurality of reference signals to produce a plurality of correlations, detect a transition between receiving the first GPS signal and receiving a second GPS signal from the GPS satellite based on a phase shift in the correlations, and if the transition is detected, compensate for the phase shift when computing a range to the GPS satellite.

Abstract: A method of estimating a position of a satellite receiver, comprising computing a weight matrix, and computing an estimated position of the satellite receiver based on the weight matrix, wherein computing the weight matrix includes computing quantities indicative of degradations experienced by satellite signals and of multipath interference, and computing the weight matrix based on the computed quantities.

Abstract: An antenna includes a waveguide having an aperture at a first end and a conducting component at a second end, the conducting component shorting the waveguide and a first set of two orthogonal dipoles, fed in quadrature, the orthogonal dipoles located near the aperture of the waveguide operating close to its dominant mode cut off frequency.

Abstract: A method for estimating hidden channel parameters of a GNSS navigation signal received in a multipath environment includes a sequential Bayesian estimation. A movement model forms the basis of the estimation and is designed especially for dynamic channel scenarios and takes into account the speeds of change and the variable life cycles of the path. The estimator is implemented as a recursive Bayesian filter for a combined determination of positions and suppression of multipaths. The binding of the delay of the direct path is taken into consideration via position and clock parameters. The method is carried out with GNSS satellite navigation receivers, e.g. GPS and Galileo. With the method, multipath error of received GNSS navigation signals is reduced. The multipath channel includes a direct path and Nm-I echo signals and each of these paths may be considered on or off for the estimation.

Abstract: A GNSS enabled communication device receives GNSS signals from GNSS satellites. The resulting GNSS baseband signals may be concurrently correlated with GNSS acquisition codes. Inter-delay products for the received GNSS signals may be generated utilizing the correlation IQ samples. The inter-delay products are utilized to calculate either an open loop or a close-loop estimate for inter-delay phase coherence of the received GNSS signals. A test statistic, generated from the inter-delay products, may be compared with a preset or dynamically determined threshold value in order to detect or declare signal degradation effects in the received GNSS signals. The early and late delays for the inter-delay phase coherence may be generalized to two or more delays. In this regard, the correlation IQ samples may be utilized to generate a correlation matrix. Variations derived from the correlation matrix may be utilized to declare or detect signal degradation effects in the received GNSS signals.

Abstract: A method and apparatus for mitigating multipath effects in a satellite signal receiver is described. In one example, measured pseudoranges are obtained from the satellite signal receiver to a plurality of satellites. For each measured pseudorange: an expected pseudorange is derived from a sequential estimation filter in the satellite signal receiver. The measured pseudorange and the expected pseudorange are differenced to compute a pseudorange residual. The measured pseudorange is applied to the sequential estimation filter only if the pseudorange residual is within a window.

Abstract: An apparatus and method correct position information of a portable terminal in a multi-path zone. The method includes determining whether the portable terminal has entered a multi-path zone, and detecting a second GPS satellite transmitting accurate position information, among one or more first GPS satellites transmitting position information to the portable terminal, when the portable terminal has entered the multi-path zone. The method also includes receiving position information of the portable terminal from the second GPS satellite, and storing coordinates of the second GPS satellite.

Abstract: A GPS receiver for tracking a GPS signal. The receiver generates a mixed GPS signal by mixing the GPS signal with an oscillator signal, generates a first correlation signal by correlating the mixed GPS signal with a reference signal, and generates a filtered GPS signal from the GPS signal. The receiver also generates a filtered reference signal from the reference signal, generates a second correlation signal by correlating the filtered GPS signal with the filtered reference signal, and a generates a combined correlation signal by combining the first correlation signal with the second correlation signal. The receiver tracks the GPS signal by adjusting the phase of the oscillator signal based on the combined correlation signal.

Abstract: A multipath signal evaluation method includes, carrying out a correlation calculation on a received signal from a positioning satellite to obtain a peak correlation value, and determining reliability for a received multipath signal by using the peak correlation value and a correlation value at a phase delayed from a peak phase in which the peak correlation is obtained.

Abstract: The location of a receiver is determined by receiving respective ranging signals from each of a plurality of transmitters at known locations. The ranging signals are cross-correlated with respective model signals to provide respective cross-correlation functions. For cross correlation functions that are determined to include multipath noise, the multipath noise is estimated and removed. Respective delays of the cross-correlation functions are estimated and the location of the receiver is inferred from the delays.

Abstract: An existence of multipath is detected accurately based on not only a C/No. A C/No (iv) of a reception signal, a pseudorange PR(iv), and a delta range DR(iv) are acquired (S101). First, as determination processing based on individual measurement values, thresholds are set thereto respectively, and the existence of multipath is detected (S102-S104). Next, as determination processing based on continuous values, an average value C/No(Av) and a standard deviation ?C/No of the C/No, and an average value DV(Av) and a standard deviation ?DV of the difference values are calculated, thresholds are similarly set thereto respectively, and the existence of multipath is determined (S105-S109). Then, if multipath is determined that it does not exist based on the individual measurement values and the continuous values, it is determined ultimately that multipath does not exist (S110).

Abstract: A method for mitigating the effects of multipath errors in GNSS devices is provided. Signals from GNSS satellites are received. Image data from an image sensor is received. Orientation data from an orientation sensor is received. The orientation data describes the orientation of the image sensor. Obstruction data is determined based on the image data. The obstruction data includes an obstruction region that indicates the sky in that region is obstructed by a structure. Based on the orientation data, obstruction data, and GNSS satellite location data, the position of GNSS satellites with respect to the obstruction region is determined. The location of the GNSS device is determined based on signals from some of the GNSS satellites and the position of GNSS satellites with respect to the obstruction region.

Abstract: Embodiments of an improved assisted global positioning system (GPS) method and system are described. Wireless access points send assistance data to GPS receivers that are integrated into cellular chipsets and other chipsets. The access points may also act as fixed location references for differential GPS (DGPS) mobile stations. Errors caused by multipath travel of the GPS signals are reduced by using fixed location reference receivers.

Abstract: A navigation receiver mounted on a moving vehicle receives navigation signals transmitted from global navigation satellites. The navigation signals are separated into direct navigation signals, navigation signals reflected from an object, and navigation signals reflected from an environmental surface. The signal separation is based on algorithms including various combinations of signal strength, change in signal strength, delay time, spectral width, change in spectral width, and user-defined thresholds. The navigation signals reflected from an environmental surface are eliminated from further processing. The position of the navigation receiver is calculated based on the direct navigation signals. The object is detected, and the position of the object is calculated, based on the navigation signals reflected from the object. If the object is determined to lie in the path of the moving vehicle, a command can be generated to avoid collision between the moving vehicle and the object.

Abstract: Systems and methods for mapping a structure detect wireless signals, including at least one multipath signal that has experienced at least one reflection against a portion of the structure prior to the detection. The wireless signals are analyzed to estimate reflection points for the multipath signal(s), and a map of at least the portion of the structure is generated based on the estimated reflection points.

Abstract: Embodiments provided herein recite methods and systems for an accuracy estimator for a position fix. In one embodiment, a solution receiver for receiving a code solution and at least one additional solution from a different solution technique is utilized. In addition, a table of metric values comprising an associated accuracy estimate for at least one characteristic of each of the code solution and the at least one additional solution is also utilized. A comparator compares the code solution and the at least one additional solution with the table of metric values. In addition, a solution orderer orders the at least one additional solution above or below the code solution dependent on whether the at least one additional solution is within a pre-defined offset distance threshold. If the at least one additional solution is outside of the distance threshold, the code solution is chosen as the final solution.

Abstract: Embodiments of an improved assisted global positioning system (GPS) method and system are described. Wireless access points send assistance data to GPS receivers that are integrated into cellular chipsets and other chipsets. The access points may also act as fixed location references for differential GPS (DGPS) mobile stations. Errors caused by multipath travel of the GPS signals are reduced by using fixed location reference receivers.

Abstract: A method and apparatus for estimating and compensating for a broad class of non-Gaussian sensor and process noise. In one example, a coded filter combines a dynamic state estimator (for example, a Kalman filter) and a non-linear estimator to provide approximations of the non-Gaussian process and sensor noise associated with a dynamic system. These approximations are used by the dynamic state estimator to correct sensor measurements or to alter the dynamic model governing evolution of the system state. Examples of coded filters leverage compressive sensing techniques in combination with error models based on concepts of compressibility and the application of efficient convex optimization processes.

Abstract: A method for reducing multipath when determining a location of a stationary or near stationary position, includes receiving a signal from an antenna moving continuously with respect to the stationary or near stationary position, the signal including a multipath component, processing the received signal including the multipath component, wherein multipath error in the received signal is reduced during the processing and determining a location of the stationary or near stationary position based on the processed received signal with the multipath error reduced.

Abstract: Systems, methods and devices for multipath mitigation are presented. Specifically, embodiments of the invention can advantageously use sensor inputs to mitigate the effect of multipath signals received at a receiver. The use of physical sensors in navigation systems is deemed particularly advantageous.

Abstract: To provide a GPS compound device having a configuration including a GPS receiver, that accurately determines abnormality in an output from the GPS receiver based on a difference between a GPS pseudorange measurement and a Doppler frequency measurement, when detecting the abnormality in the outputs from the GPS receiver, while avoiding continuation of the abnormality at the time of the abnormality determination resulting from estimation errors of the GPS pseudorange measurement and the Doppler frequency measurement. When the abnormality of the outputs from the GPS receiver are detected, an abnormal period is counted. When the count value is below a predetermined threshold, the outputs from the GPS receiver are treated as abnormal, and after it exceeded the threshold, the outputs from the GPS receiver are treated as normal. Thus, the abnormality of the outputs from the GPS receiver can be determined accurately.

Abstract: A method of multipath error suppression in a satellite navigation receiver, including steps of navigation satellites signals searching, receiving and processing complex signals from each satellite, tracking found signals with a following-up open loop and determining coordinates, receiver velocity and exact time based on measurements of direct and reflected signal delay and Doppler frequency, the method including: forming, on the basis of navigation parameters, a two-dimensional accumulated power grid, calculating single-path signal corrections using the centered accumulated power grid determining, whether a multipath is presented, and performing, in case of positive result of this determination, improvement of corrections using weights, wherein, performing improvement of corrections using weights is carried out by forming a likelihood function on the basis of a centered accumulated powers vector, and correction is performed according to the found likelihood function global maximum.

Abstract: The integrity of operation of a GPS precision aircraft approach and landing system may be compromised by error producing effects of reflected multipath signals. An integrity monitor antenna system as disclosed may utilize both attenuation and shadowing of reflected multipath GPS signals to achieve extreme multipath mitigation of the order of 50 dB suppression. An antenna with a right-hand circular polarization pattern having a sharp cut off at the horizon may provide 30 dB suppression of reflected multipath signals. A signal absorbent ground plane bed of defined dimensions may provide 20 dB attenuation of incident multipath signals. A signal/processor may be employed to derive position error data for integrity monitoring, based upon differentials between a known fixed location and a current GPS-indicated location. Communication of identification of a subset of particular GPS satellites for common usage may also reduce potential error levels.

Abstract: A positioning method includes: capturing a satellite signal from a positioning satellite; predicting a state vector including a position of a positioning device and a velocity of the positioning device based on the satellite signal; predicting a first distance-equivalent value indicating a distance between the positioning satellite and the positioning device; measuring a second distance-equivalent value indicating a distance between the positioning satellite and the positioning device; calculating an observed value indicating a difference between the first distance-equivalent value and the second distance-equivalent value; setting a measurement error for the positioning satellite based on a signal strength of the satellite signal; changing the measurement error based on a capture data indicating a data of capturing of the satellite signal; and correcting the state vector using the observed value, and the changed measurement error.

Abstract: A method of estimating a position of a satellite receiver, comprising computing a weight matrix, and computing an estimated position of the satellite receiver based on the weight matrix, wherein computing the weight matrix includes computing quantities indicative of degradations experienced by satellite signals and of multipath interference, and computing the weight matrix based on the computed quantities.

Abstract: A system for measuring the pseudo range from a target GPS sensor to a designated navigational satellite, for use in a satellite positioning system (SPS) is comprised of multiple GPS sensors for receiving and recording portions of the signals transmitted by designated navigational satellites, the recordings referred to as datagrams; and means for transmitting the datagrams to a datagram processing facility wherein the pseudo range from the target GPS sensor to the designated navigational satellite is derived.

Abstract: A positioning device for receiving a satellite signal corresponding to a signal from a positioning satellite including a multipath recurrent district elevation information storing unit for storing multipath recurrent district elevation information indicating the elevation of a multipath recurrent district as elevation information of plural divisional areas, an elevation information obtaining position information generating unit for receiving the satellite signals and generating elevation information obtaining position information to obtain the elevation information, an elevation information obtaining unit for obtaining the elevation information of the divisional area corresponding to the elevation information obtaining position information and an elevation information using present position information generating unit for generating elevation information using present position information indicating the present position on the basis of the satellite signals and the elevation information.

Abstract: A multipath signal evaluation method includes, carrying out a correlation calculation on a received signal from a positioning satellite to obtain a peak correlation value, and determining reliability for a received multipath signal by using the peak correlation value and a correlation value at a phase delayed from a peak phase in which the peak correlation is obtained.

Abstract: A positioning apparatus for positioning a current position based on satellite signals from positioning satellites includes: satellite signal receiving means, correlation information generating means, tentative code peak position information generating means, statistical processing range information generating means, statistical information generating means for generating statistical information by performing a statistical processing of the correlation values within the statistical processing range for each partial range specified as a limited range rather than the statistical processing range, beginning position information generating means, and direct wave code peak corresponding position information generating means for generating direct wave code peak corresponding position information which indicates a direct wave code peak corresponding position corresponding to a direct wave code peak, which is the maximum correlation value between the direct wave and the replica satellite signal, based on the beginning

Abstract: Systems and methods for detecting global positioning system (GPS) measurement errors are provided. In this regard, a representative system, among others, includes a navigation device that is configured to receive GPS signals from signal sources, the navigation device being configured to calculate pseudoranges (PRs) and delta ranges (DRs) based on the received GPS signals, the navigation device including a consistency check algorithm that is configured to: determine mismatches between the respective calculated PRs and DRs, and indicate that an error exists in the respective calculated PRs and DRs based on their mismatch and mismatch accumulations. This algorithm can be independent of navigation state and is capable of detecting slow-changing errors.

Abstract: A method of multipath error suppression in a satellite navigation receiver, including steps of navigation satellites signals searching, receiving and processing complex signals from each satellite, tracking found signals with a following-up open loop and determining coordinates, receiver velocity and exact time based on measurements of direct and reflected signal delay and Doppler frequency, the method including: forming, on the basis of navigation parameters, a two-dimensional accumulated power grid, calculating single-path signal corrections using the centered accumulated power grid determining, whether a multipath is presented, and performing, in case of positive result of this determination, improvement of corrections using weights, wherein, performing improvement of corrections using weights is carried out by forming a likelihood function on the basis of a centered accumulated powers vector, and correction is performed according to the found likelihood function global maximum.