Abstract: Synchronizing the local time of beacons. Systems and methods discipline a high-stability local clock of a designated beacon within a geographic region to a network time, and synchronize a local clock of another beacon within the geographic region to the network time.

Abstract: A receiver (100) is provided for signals of different signal strengths and modulated with respective pseudorandom noise (PN) codes. The receiver (100) includes a correlator circuit (120) operable to correlate the signals with a selectable locally-issued PN code having a Doppler and a code lag to produce a peak, the correlator circuit (120) being subject to cross correlation with a distinct PN code carried by least one of the signals that can produce cross correlation; and a cross correlation circuit (370, 400) operable to generate a variable comparison value related to the cross correlation as a function of values representing a Doppler difference and a code lag difference between the locally-issued PN code and the distinct PN code, and to use the variable comparison value to reject the peak as invalid from cross correlation or to pass the peak as a valid received peak.

Abstract: Reducing power consumption of a receiver in association with estimating the receiver's position using ranging signals. Systems and methods may determine power reduction strategy information, identify a power reduction strategy using the determined power reduction strategy information, and place one or more modules of the receiver into a reduced power state using the identified power reduction strategy. The power reduction strategy may result in powering off different circuitry of the receiver at different times, and under different circumstances.

Abstract: This application is directed to a passively-cooled electronic device including a housing, a plurality of electronic assemblies and a plurality of thermally conductive parts. The electronic assemblies are enclosed in the housing, and include a first electronic assembly and a second electronic assembly. The first and second electronic assemblies are disposed proximately to each other within the housing, and the second electronic assembly is substantially sensitive to heat, including heat generated by operation of the first electronic assembly. The thermally conductive parts are coupled between the first electronic assembly and the housing, and configured to create a first plurality of heat conduction paths to conduct the heat generated by the first electronic assembly away from the second electronic assembly without using a fan. At least a subset of the thermally conductive parts mechanically supports one or both of the first and second electronic assemblies.

Abstract: A position location system comprises transmitters that broadcast positioning signals. Each broadcasted positioning signal comprises a pseudorandom ranging signal. The position location system includes a remote receiver that acquires and measures the time of arrival of the positioning signals received at the remote receiver. During an interval of time, at least two positioning signals are transmitted concurrently by the transmitters and received concurrently at the remote receiver. The two positioning signals have carrier frequencies offset from one another by an offset that is less than approximately twenty-five percent of the bandwidth of each positioning signal of the two positioning signals. Cross-interference between the positioning signals is reduced by tuning the remote receiver to a frequency of a selected signal of the two positioning signals and correlating the selected signal with a reference pseudorandom ranging signal matched to a transmitted pseudorandom ranging signal of the selected signal.

Abstract: Using estimates of a receiver's altitude to determine where a receiver is located and to refine a positioning system's estimate of a receiver's position. Systems and methods determine whether a receiver is inside or outside a building, and may use the determination to confirm or adjust an initial estimate of the receiver's position. Various approaches for making the determination and for assessing the initial estimate of the receiver's position are described.

Abstract: Synchronizing the local time of beacons using two way time transfer methods and hardware enabling such methods. Certain systems incorporate receive hardware into beacon circuitry used for transmitting signals so that the beacon can transmit RF signals during transmission periods, and can also receive RF signals from other beacons during non-transmission periods. Receive hardware may be incorporated into beacon circuitry such that the beacon receives an incoming signal and passes that incoming signal to a digital pre-distortion linearization module, which can process that received signal.

Abstract: A position location system comprises transmitters that broadcast positioning signals. Each broadcasted positioning signal comprises a pseudorandom ranging signal. The position location system includes a remote receiver that acquires and measures the time of arrival of the positioning signals received at the remote receiver. During an interval of time, at least two positioning signals are transmitted concurrently by the transmitters and received concurrently at the remote receiver. The two positioning signals have carrier frequencies offset from one another by an offset that is less than approximately twenty-five percent of the bandwidth of each positioning signal of the two positioning signals. Cross-interference between the positioning signals is reduced by tuning the remote receiver to a frequency of a selected signal of the two positioning signals and correlating the selected signal with a reference pseudorandom ranging signal matched to a transmitted pseudorandom ranging signal of the selected signal.

Abstract: Using estimates of a receiver's altitude to determine where a receiver is located and to refine a positioning system's estimate of a receiver's position. Systems and methods determine whether a receiver is inside or outside a building, and may use the determination to confirm or adjust an initial estimate of the receiver's position. Various approaches for making the determination and for assessing the initial estimate of the receiver's position are described.

Abstract: Systems and methods for improving performance in terrestrial and satellite positioning systems. Signal processing systems and methods are described for selecting, from among a set of codes, certain codes having desired autocorrelation and/or cross-correlation properties. Systems and methods for generating, encoding, transmitting, and receiving signals using the selected codes are also described.

Abstract: Synchronizing the local time of beacons using two way time transfer methods and hardware enabling such methods. Certain systems incorporate receive hardware into beacon circuitry used for transmitting signals so that the beacon can transmit RF signals during transmission periods, and can also receive RF signals from other beacons during non-transmission periods. Receive hardware may be incorporated into beacon circuitry such that the beacon receives an incoming signal and passes that incoming signal to a digital pre-distortion linearization module, which can process that received signal. Methods for controlling whether a beacon transmits RF signals or receives RF signals are also discussed, as are methods for using RF signals received from other beacons for synchronization.

Abstract: Positioning systems and methods for estimating an altitude of a receiver. In some embodiments, pressure and temperature information from a network of sensors is received by the receiver, and the pressure and temperature information from the network of sensors is used along with pressure information measured at a position of the receiver to estimate the altitude of the receiver.

Abstract: Systems and methods for estimating error associated with one or more range measurements that are used to estimate the position of a receiver. Estimations of range error may be based on surveyed range errors associated with locations near the position of the receiver. Estimations of range error may alternatively be based on comparisons of actual movement by the receiver to estimated movement between estimates of the receiver's positions.

Abstract: Interference detection and mitigation using maximal ratio combining in the correlation domain. Systems and methods for interference detection and mitigation using maximal ratio combining in the correlation domain may receive a plurality of copies of a positioning signal, compute a plurality of correlation functions using the received positioning signals; weight the plurality of correlation functions using a plurality of weights that are proportional to the quality of the plurality of correlation functions, and generate a combined correlation function by combining the weighted correlation functions.

Abstract: Devices, systems, and methods for sending positional information from transmitters/beacons. In one implementation a transmitter generates a range block including a ranging signal and a hybrid block including positioning data, and sends the range block and hybrid block at different times. A user device may receive signals from a plurality of transmitters and generates position/location information using trilateration and measured altitude information in comparison with transmitter altitude information.

Abstract: Embodiments describe determining position by selecting a set of digital pseudorandom sequences. The magnitudes of the cross-correlation between any two sequences of the chosen set are below a specified threshold. A subset of digital pseudorandom sequences are selected from the set such that the magnitudes of the autocorrelation function of each member of the subset, within a specified region adjacent to the peak of the autocorrelation function, are equal to or less than a prescribed value. Each transmitter transmits a positioning signal, and at least a portion of the positioning signal is modulated with at least one member of the subset. At least two transmitters of the plurality of transmitters modulate respective positioning signals with different members of the subset of digital pseudorandom sequences.

Abstract: Systems and methods are described for determining position of a receiver. The positioning system comprises a transmitter network including transmitters that broadcast positioning signals. The positioning system comprises a remote receiver that acquires and tracks the positioning signals and/or satellite signals. The satellite signals are signals of a satellite-based positioning system. A first mode of the remote receiver uses terminal-based positioning in which the remote receiver computes a position using the positioning signals and/or the satellite signals. The positioning system comprises a server coupled to the remote receiver. A second operating mode of the remote receiver comprises network-based positioning in which the server computes a position of the remote receiver from the positioning signals and/or satellite signals, where the remote receiver receives and transfers to the server the positioning signals and/or satellite signals.

Abstract: Positioning systems and methods for estimating an altitude of a receiver. In some embodiments, pressure and temperature information from a network of sensors is received by the receiver, and the pressure and temperature information from the network of sensors is used along with pressure information measured at a position of the receiver to estimate the altitude of the receiver.

Abstract: Reducing power consumption of a receiver in association with estimating the receiver's position using ranging signals. Systems and methods may determine power reduction strategy information, identify a power reduction strategy using the determined power reduction strategy information, and place one or more modules of the receiver into a reduced power state using the identified power reduction strategy. The power reduction strategy may result in powering off different circuitry of the receiver at different times, and under different circumstances.

Abstract: Devices, systems, and methods for sending positional information from transmitters/beacons. In one implementation a transmitter generates a range block including a ranging signal and a hybrid block including positioning data, and sends the range block and hybrid block at different times. A user device may receive signals from a plurality of transmitters and generates position/location information using trilateration and measured altitude information in comparison with transmitter altitude information.