269 results about "Integer ambiguity" patented technology

A real-time integrated vehicle positioning method and system with differential GPS can substantially solve the problems encountered in either the global positioning system-only or the inertial navigation system-only, such as loss of global positioning satellite signal, sensitivity to jamming and spoofing, and an inertial solution's drift over time. In the present invention, the velocity and acceleration from an inertial navigation processor of the integrated GPS/INS system are used to aid the code and carrier phase tracking of the global positioning system satellite signals, so as to enhance the performance of the global positioning and inertial integration system, even in heavy jamming and high dynamic environments. To improve the accuracy of the integrated GPS/INS navigation system, phase measurements are used and the idea of the differential GPS is employed. However, integer ambiguities have to be resolved for high accuracy positioning. Therefore, in the present invention a new on-the-fly ambiguity resolution technique is disclosed to resolve double difference integer ambiguities. The real-time fully-coupled GPS/IMU vehicle positioning system includes an IMU (inertial measurement unit), a GPS processor, and a data link which are connected to a central navigation processor to produce a navigation solution that is output to an I/O (input/output) interface.

Computer-implemented methods and apparatus are presented for processing data collected by at least two receivers from multiple satellites of multiple GNSS, where at least one GNSS is FDMA. Data sets are obtained which comprise a first data set from a first receiver and a second data set from a second receiver. The first data set comprises a first FDMA data set and the second data set comprises a second FDMA data set. At least one of a code bias and a phase bias may exist between the first FDMA data set and the second FDMA data set. At least one receiver-type bias is determined, to be applied when the data sets are obtained from receivers of different types. The data sets are processed, based on the at least one receiver-type bias, to estimate carrier floating-point ambiguities. Carrier integer ambiguities are determined from the floating-point ambiguities. The scheme enables GLONASS carrier phase ambiguities to be resolved and used in a combined FDMA/CDMA (e.g., GLONASS/GPS) centimeter-level solution. It is applicable to real-time kinematic (RTK) positioning, high-precision post-processing of positions and network RTK positioning.

Apparatus for measuring surveying parameters, such as distances and angular displacements between an instrument survey station and a mobile survey station, with improved accuracy. The invention combines a differential satellite positioning system (DSATPS), available with positioning systems such as GPS and GLONASS, with electromagnetic measurements of distances and optically encoded angles by a conventional electro-optical survey instrument to provide survey measurements that can be accurate to within a few millimeters in favorable situations. The DSATPS relies upon pseudorange measurements or upon carrier phase measurements, after removal of certain phase integer ambiguities associated with carrier phase SATPS signals. The SATPS may be retrofitted within the housing of the conventional electro-optical instrument. In a first approach, a remote station provides DSATPS corrections for the mobile station and/or for the instrument station. In a second approach, the mobile station provides DSATPS corrections for itself and for the instrument station. In a third approach, the instrument station provides DSATPS corrections for itself and for the mobile station.

A global navigation system includes a first navigation receiver located in a rover and a second navigation receiver located in a base station. Single differences of measurements of satellite signals received at the two receivers are calculated and compared to single differences derived from an observation model. Anomalous measurements are detected and removed prior to performing computations for determining the output position of the rover and resolving integer ambiguities. Detection criteria are based on the residuals between the calculated and the derived single differences. For resolving integer ambiguities, computations based on Cholessky information Kalman filters and Householder transformations are advantageously applied. Changes in the state of the satellite constellation from one epoch to another are included in the computations.

The invention relates to a method for measuring attitude of a carrier by using an additional constraint condition of a satellite, which comprises the following steps of: establishing a linearization carrier phase double-difference model for each baseline of an attitude measuring system, and determining the integer ambiguity; expanding a search space, and determining a trigonometric function constraint and a base length constraint; substituting a constraint condition containing the maximum boundary and the minimum boundary into a search process to obtain an upper bound and a lower bound of a formula ambiguity candidate value; performing a comparison according to the boundaries obtained in the search process and an original constraint, and selecting a smaller boundary as the boundary of the ambiguity; and selecting ambiguity candidate values, wherein if the ambiguity candidate values are more than one, two groups of the ambiguity candidate values with the minimum residual errors are selected to perform a verification of the next step, and the candidate values passing through a significance test are fixed solutions of the integer ambiguity. The attitude of the carrier is obtained by further using an attitude measurement algorithm through the fixed solutions. The method has the advantages of reducing the search times, reducing influences caused by noises and significantly improving the measuring accuracy and the success ratio.

The invention provides a double-antenna GNSS (Global Navigation Satellite System)/INS (Inertial Navigation System) deeply integrated navigation method and device. The device comprises a power supply module, an MEMS (Micro Electro Mechanical System) inertial measurement unit, a radio frequency module, an FPGA (Field Programmable Gate Array) module, a DSP (Digital Signal Processor) module and at least two antennas. According to the device, with the assistance of an INS, the probability of cycle slip of the GNSS can be reduced effectively, the integer ambiguity searching space of the GNSS is reduced, attitude measurement information is guaranteed to be continuously outputted, and the tracking loop robustness of the GNSS is enhanced; and with the assistance of a double-antenna GNSS, quick initial alignment of the INS can be realized, the attitude observability of the INS is improved, and the attitude divergence of the INS is inhibited.

A carrier phase GPS positioning device is disclosed, which acquires a carrier phase accumulation value of satellite signals at one time on the mobile station side, associates plural carrier phase accumulation values on the reference station side at plural times prior to the one time with the carrier phase accumulation value on the mobile station side, and estimates an integer ambiguity included in the carrier phase accumulation value of signals transmitted from the satellite received by the mobile station.

A system for determining the heading and/or attitude of a body receives radio waves from a plurality of position-fixing satellites using at least three antennas fixedly mounted at different positions of the body. To reliably obtain integer ambiguity solutions of carrier phases of the radio waves in a shorter time, the system directly determines integer ambiguities from attitude angle data obtained by an IMU attitude processing section when the integer ambiguities are to be redetermined in the event of an interruption of the received radio waves or a change in the combination of satellites to be used. This system provides a user with highly accurate uninterrupted heading and/or attitude angle information.

An attitude angle detecting apparatus receives radio waves transmitted from a plurality of position-fixing satellites with multiple antennas located at specific positions of a mobile unit, determines relative positions of the antennas and detects the heading and attitude of the mobile unit by determining carrier phase ambiguities quickly and accurately. When it is needed to redetermine integer ambiguities after recovery from an interruption of the radio waves from the position-fixing satellites or as a result of a change in combination of the position-fixing satellites, for example, the attitude angle detecting apparatus redetermines the integer ambiguities by using attitude angles and an attitude angle error covariance obtained from previous observation. This enables the attitude angle detecting apparatus to uninterruptedly obtain information on the heading and attitude of the mobile unit.

Method for precise GNSS positioning system with improved ambiguity estimation. The method is based on the realization that, especially during convergence, the estimated float ambiguities are biased when estimated simultaneously with the ionosphere parameters. The “ionosphere-like” biases can be separated from the actual float ambiguities by using the fixed wide-lane (or extra wide-lane) integer ambiguities. The original real-valued ambiguities (e.g., one of L1, L2 and L5 in the GPS case) are corrected using the corresponding biases, resulting in reliable float ambiguities that are taken as input in the next processing step.

A long baseline satellite formation GNSS relative positioning method based on ambiguity fixing is provided in order to improve the success rate of ambiguity fixing and the accuracy of relative positioning results. According to the technical scheme, the method comprises the following steps: first, collecting and pre-processing input data, and determining the absolute general orbit of a formation satellite; then, eliminating the geometric distance and clock error in differential observation data, estimating a single-difference phase ambiguity float solution and a single-difference ionosphere delay parameter, carrying out double-difference transform to get a double-difference wide-lane ambiguity float solution and a covariance matrix, and fixing the double-difference wide-lane integer ambiguity and the double-difference narrow-lane integer ambiguity; and finally, outputting the relative positioning result of ambiguity fixing. By adopting the method of the invention, the problem that ambiguity fixing strongly depends on a pseudo code with low observation precision due to equally-weighted pseudo code and phase processing in M-W combination in the traditional method is avoided, the success rate of long baseline satellite formation GNSS relative positioning ambiguity fixing and the accuracy of final relative positioning results are improved, calculation is stable, and the reliability of relative positioning results is improved.

The present invention includes a method for generating an ambiguity-resolved, refraction-corrected, and noise-minimized carrier-phase measurement. The method includes forming a first composite measurement using GPS carrier-phase measurements on the L1, L2 and L5 frequencies. To reduce the noise in the first composite measurement, the method further includes forming a second composite measurement using GPS carrier-phase measurements on at least two of the three GPS carrier frequencies. The second composite measurement is formed to have a small multi-path noise therein so that it can be used to smooth the first composite measurement so that the multipath noise is minimized.

A method for providing and applying Precise Point Positioning-Integer Ambiguity Resolution (PPP-IAR) corrections for a Global Navigation Satellite System (GNSS). In a GNS signal correction system, PPP-IAR corrections (ambiguities plus receiver and satellite hardware delays) are calculated based on observation data (P_i,a, Φ_i,a) of n satellites for individual reference stations using a functional model, and these individual PPP-IAR corrections are merged into one single and larger set of PPP-IAR corrections. In a broadcast system, the (merged) PPP-IAR corrections are encoded at a System Control Centre (SCC) and transmitted to mobiles. In a mobile system a similar functional model is used to calculate a correction Δx to an a priori position.

A primary phase measurement device measures a first carrier phase and a second carrier phase of carrier signals received by the location-determining receiver. A secondary phase measurement device measures the third carrier phase and the fourth carrier phase of other carrier signals. A real time kinematic engine estimates a first integer ambiguity set associated with the measured first carrier phase and a second integer ambiguity set associated with the measured second carrier phase. The real time kinematic engine estimates a third ambiguity set associated with the measured third carrier phase and a fourth ambiguity set associated with the measured fourth carrier phase. A compensator is capable of compensating for the inter-channel bias in at least one of the third ambiguity set and the fourth ambiguity set by modeling a predictive filter in accordance with various inputs or states of the filter estimated by an estimator.

The invention discloses an adaptive genetic algorithm-based single-frequency GNSS integer ambiguity acquisition method. The method includes the following steps: step 1: acquiring the observed data of a GNSS carrier phase, and establishing a double-difference observation equation for the GNSS carrier phase; step 2: according to the double-difference observation equation obtained in step 1, utilizing the least square method to acquire the float solution and corresponding covariance matrix of GNSS integer ambiguity; step 3: utilizing known base length as a constraint condition to determine the search space of integer ambiguity; step 4: utilizing the whitening filter method to decorrelate the float solution and covariance matrix of integer ambiguity obtained in step 2; step 5: according to anobjective function, determining a fitness function, determining each operating parameter in the adaptive genetic algorithm, finally, introducing the adaptive genetic algorithm into fast solution on integer ambiguity, and searching the optimal solution of integer ambiguity.

A new method for bias estimation on multiple frequencies with a Kalman filter is proposed. It consists of four steps: First, a least-squares estimation of ranges, ionospheric delays, ambiguities, receiver phase biases and satellite phase biases is performed. The code biases are absorbed in the ranges and ionospheric delays, and a subset of ambiguities is mapped to the phase biases to remove linear dependencies between the unknown parameters. In a second step, the accuracy of the bias estimates is efficiently improved by a Kalman filter. The real-valued a posteriori ambiguity estimates are decorrelated by an integer ambiguity transformation to reduce the time of ambiguity resolution. Once the float ambiguities have sufficiently converged, they are fixed sequentially in a third step. Finally, a second Kalman filter is used to separate the receiver and satellite code biases and the tropospheric delays from the ranges.

The invention discloses a high precision positioning method based on a PPP algorithm as well as a system and relates to the field of GNSS high precision positioning application. Centimeter-level highprecision positioning can be realized by being independent of a ground positioning base station, only depending on a mobile terminal, utilizing a double frequency GNSS carrier phase and an observed pseudorange value and combining a GNSS precise orbit and clock correction. The system comprises a GNSS double frequency signal receiving module, a wireless wide area network module, a low orbit navigation enhanced satellite signal receiving module and a microprocessor. The positioning method obtains the original pseudorange and carrier phase observation data by adopting GNSS double frequency observation data and GNSS precise correction, then fixes integer ambiguity by utilizing an LAMBDA algorithm and finally performs recursion and convergence on an ionized layer combined observation linear equation by adopting an expansion Kalman filtering equation, thus location information is obtained. The method and system which are disclosed by the invention have the advantages of convenience in use, high reliability and low cost.

Embodiments are directed to performing integer ambiguity validation in carrier phase differential positioning and to calculating a protection level for safety-of-life applications. In one scenario, a computer system accesses double-differenced pseudorange measurements and carrier phase measurements which are combined to produce an estimate of the relative position between receivers. Integer bootstrapping is performed to produce fixed range ambiguity estimates that are integer multiples of a carrier signal wavelength. A validation threshold is then established based on a statistical model of the pseudorange and carrier wave measurements that ensures that a specified probability of correct ambiguity resolution is met. A data-driven validation is initiated on the difference between the float range ambiguity estimates and the fixed range ambiguity estimates to validate the correctness of the fixed range ambiguity estimate. Then, upon determining that the fixed range ambiguity estimates are valid, the estimate of the relative position between the receivers is corrected.