Abstract: The invention provides a method and apparatus to optimally estimate and adaptively compensate the temperature-induced frequency drift of a crystal oscillator in a navigational signal receiver. A Read-Write memory encodes two tables, one for looking up frequency drift values versus temperature readings and another one for valid data confirmation on the first table. The initially empty look-up table is gradually populated with frequency drift values while the receiver computes the frequency drift along with its position. During initial start of the receiver or re-acquisition of satellite signals, the stored frequency drift value corresponding to the current temperature is used. If no valid frequency drift value is available, the frequency drift value is computed based on the existing frequency drift values in the table. This invention reduces the Time-To-First-Fix (TTFF) of the receiver and enables the receiver to self-calibrate, thus no additional factory calibration would be necessary.

Abstract: Provided herein are methods and system for enabling a navigation receiver to generate receiver specific satellite orbital models based on relatively small sets of parameters obtained from a server. In an embodiment, a set of parameters for a satellite includes a force parameter (e.g., solar radiation pressure), initial condition parameters (e.g., satellite position and velocity at a time instance) and time correction coefficients, which the receiver uses in a numerical integration to predict the position of the satellite. The set of parameters needed for the integration is small compared to current methods which require transmission of a complete set of ephemeris and other parameters for each satellite. Since the set of parameters is relatively small, it requires less communication resources to transmit compared to current methods. Further, the integration based on the small set of parameters enables the receiver to predict satellite orbits with low computational load.

Abstract: The present invention provides systems and methods for implementing narrowly spaced correlators to mitigate multipath error, and systems and methods for adaptively changing the correlator spacing for varying multipath conditions. In an embodiment, two sets of correlators with the same code frequency but different code phases are used to implement an adjustable correlator spacing. The correlator spacing is determined by the code phase difference between the two sets of correlators, which can be adjusted, e.g., by adjusting the code phase values of Numerically Controlled Oscillators (NCOs). An advantage of embodiments of the present invention is that they can achieve much narrower correlator spacings than conventional techniques, e.g., by making the code phase difference between the two sets of correlators very small. Further, the correlator spacing can be adjusted for varying multipath conditions, whereas the correlator spacing in conventional techniques is fixed.

Abstract: The present invention provides systems and methods that enable a standalone receiver capable of downloading navigation data under weak signal conditions. In an embodiment, a standalone navigation receiver generates predicted satellite orbits based on the tracking history of the satellites stored in the receiver. The tracking history comprises historical navigation data previously received from the satellites. The receiver uses the predicted satellite orbit to generate navigation data such as ephemeris and almanac. Since the predicted satellite is accurate, the generated navigation data is similar to the navigation data transmitted by the navigation satellites, and can therefore be used by the receiver to correct the downloaded navigation data bits. Thus many of the bits of a downloaded navigation word, especially the higher order significant bits of the word can be corrected. The remaining bit errors can be resolved based on a parity check of the word.

Abstract: The present invention provides methods and system for enabling a standalone navigation receiver capable of generating receiver specific predicted satellite orbits based on historical navigation data collected by and stored in the receiver. Thus, the navigation receiver is able to use the predicted satellite orbits to obtain better Time-To-First-Fix (TTFF) and position accuracy without the need of connecting to a remote server and the associated communications system. In an embodiment, a standalone navigation receiver having sufficient memory collects navigation data from navigation satellites and generates predicted satellite orbits using the collected navigation data. Under weak signal conditions when decoding of the navigation data is not possible, the receiver uses the predicted satellite orbits to predict the accurate satellite positions or the set of ephemeris and the associated pseudoranges. The predicted orbits may be accurate for several days without the reception of broadcast ephemeris.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. The ADAPT-RTK Technology (Automatic Decorrelation and Parameter Tuning Real-Time Kinematic technology) is described using an innovative decorrelation algorithm to decorrelate the correlation between L1 and L2 measurements through a functional model and a stochastic model reducing the impact on performance of distance dependent biases.

Abstract: The present invention provides a method and apparatus for a satellite navigation receiver to lock onto satellite signals in the cold start mode with no information on the receiver position, the satellite position, or time estimates stored in the receiver's memory. All satellites in a positioning system are divided into groups based on the satellite constellation structure. In an embodiment, the positioning system is the Global Positioning System (GPS) and all GPS satellites are divided into three groups. During initialization of the receiver, the satellites are searched per group to lock onto at least one satellite signal. Other satellites are then searched in a given order based on their respective distance or proximity to the first satellite acquired. This method reduces the Time-to-First-Fix (TTFF) ordinarily required by conventional receivers in the cold start mode.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. The ADAPT-RTK Technology (Automatic Decorrelation and Parameter Tuning Real-Time Kinematic technology) is described using an innovative decorrelation algorithm to decorrelate the correlation between L1 and L2 measurements through a functional model and a stochastic model reducing the impact on performance of distance dependent biases.

Abstract: The invention presented in this disclosure gives methods to estimate and compensate for the multi-path in a typical navigational or spread spectrum receiver. The multi-path delay is estimated based on the outputs of different correlators of the receiver. Unlike three correlators normally used, the present disclosure uses five correlators, namely, Early2 (E2), Early1 (E1), Prompt (P), Late1 (L1) and Late2 (L2). The possible multi-path scenarios are classified into six different cases depending upon the reflected signal delay and the errors are computed. Further, the algorithm in the present disclosure can be extended to any correlators spacing.

Abstract: A Global Navigation Satellite System (GNSS) receiver and associated method capable of tracking weak GNSS signals from a plurality of GNSS satellites. In a preferred embodiment, code and carrier tracking loops are initially closed around the code phase, carrier frequency, and data bit edge estimates handed over from an acquisition mode. In subsequent tracking, early, prompt, and late copies of the code replica are correlated with the incoming signal. The prompt correlations are coherently integrated over an extended updating interval for data bit edge and sign estimation as well as for carrier phase and frequency error discrimination whereas the early and late correlations are used for code error discrimination. Code delay and carrier phase and frequency errors are used to update the code and carrier tracking loop filters. Together with data bits, they form observables of a GNSS signal's time and frequency parameters for timing and position fixing.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. A high precision GPS-RTK system using the present novel techniques is initialized instantaneously or near instantaneously. To improve the computational efficiency and to improve the reliability of the procedure, advances in data functional and stochastic modeling, validation criteria, adaptation and system design were achieved. A position estimate using an integrated method is determined. Ambiguity resolution of the position estimate is enhanced by applying a quality control procedure using derived validation criteria. A second position estimate based on the enhanced ambiguity resolution is derived.

Abstract: The invention provides a method and apparatus to optimally estimate and adaptively compensate the temperature-induced frequency drift of a crystal oscillator in a navigational signal receiver. A Read-Write memory encodes two tables, one for looking up frequency drift values versus temperature readings and another one for valid data confirmation on the first table. The initially empty look-up table is gradually populated with frequency drift values while the receiver computes the frequency drift along with its position. During initial start of the receiver or re-acquisition of satellite signals, the stored frequency drift value corresponding to the current temperature is used. If no valid frequency drift value is available, the frequency drift value is computed based on the existing frequency drift values in the table. This invention reduces the Time-To-First-Fix (TTFF) of the receiver and enables the receiver to self-calibrate, thus no additional factory calibration would be necessary.

Abstract: The present invention provides a method and apparatus for a satellite navigation receiver to lock onto satellite signals in the cold start mode with no information on the receiver position, the satellite position, or time estimates stored in the receiver's memory. All satellites in a positioning system are divided into groups based on the satellite constellation structure. In an embodiment, the positioning system is the Global Positioning System (GPS) and all GPS satellites are divided into three groups. During initialization of the receiver, the satellites are searched per group to lock onto at least one satellite signal. Other satellites are then searched in a given order based on their respective distance or proximity to the first satellite acquired. This method reduces the Time-to-First-Fix (TTFF) ordinarily required by conventional receivers in the cold start mode.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. A high precision GPS-RTK system using the present novel techniques is initialized instantaneously or near instantaneously. To improve the computational efficiency and to improve the reliability of the procedure, advances in data functional and stochastic modeling, validation criteria, adaptation and system design were achieved. A position estimate using an integrated method is determined. Ambiguity resolution of the position estimate is enhanced by applying a quality control procedure using derived validation criteria. A second position estimate based on the enhanced ambiguity resolution is derived.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. The ADAPT-RTK Technology (Automatic Decorrelation and Parameter Tuning Real-Time Kinematic technology) is described using an innovative decorrelation algorithm to decorrelate the correlation between L1 and L2 measurements through a functional model and a stochastic model reducing the impact on performance of distance dependent biases.

Abstract: A method of, apparatus for, and computer-readable medium for rapid, real time kinematics determination requiring lowered information transmission for position updates than traditional RTK systems. Position signals are received from a base station and roving system and a compressed position signal is received from the base station. A position estimate using an integrated method is determined using the received position signals from the base station and the roving system and the compressed position signal from the base station. Ambiguity resolution of the position estimate is enhanced by applying a quality control procedure using derived validation criteria. A second position estimate is derived based on the enhanced ambiguity resolution. Because of the use of the compressed position signal smaller transmissions may be performed at a more rapid rate providing a higher position update rate.

Abstract: A method of and computer-readable medium containing instructions for high accuracy, reliable position determination. A high precision GPS-RTK system using the present novel techniques is initialized instantaneously or near instantaneously. To improve the computational efficiency and to improve the reliability of the procedure, advances in data functional and stochastic modeling, validation criteria, adaptation and system design were achieved. A position estimate using an integrated method is determined. Ambiguity resolution of the position estinate is enhanced by applying a quality control procedure using derived validation criteria. A second position estimate based on the enhanced ambiguity resolution is derived.

Abstract: A method of, apparatus for, and computer-readable medium for rapid, real time kinematics determination requiring lowered information transmission for position updates than traditional RTK systems. Position signals are received from a base station and roving system and a compressed position signal is received from the base station. A position estimate using an integrated method is determined using the received position signals from the base station and the roving system and the compressed position signal from the base station. Ambiguity resolution of the position estimate is enhanced by applying a quality control procedure using derived validation criteria. A second position estimate is derived based on the enhanced ambiguity resolution. Because of the use of the compressed position signal smaller transmissions may be performed at a more rapid rate providing a higher position update rate.