Abstract: Determining which reference-level pressures, from among a plurality of available reference-level pressures, are used when estimating an altitude of a mobile device. Different systems and methods determine isobars based on reference-level pressures of weather stations, and then use the isobars in different ways to identify particular reference-level pressures for use in estimated an altitude of a mobile device. One approach determines the smallest distance between an initial estimated position of a mobile device and a neighboring isobar, and then uses that distance to identify reference-level pressures. Another approach identifies reference-level pressures between an isobar on which an initial estimated position of a mobile device is location and a neighboring isobar. Yet another approach compares the number of identified reference-level pressures and/or locations of the identified reference-level pressures against threshold conditions before determining which reference-level pressures to use.

Abstract: Determining calibration values for atmospheric sensors that provide measured pressures used for estimating altitudes of mobile devices. Particular systems and methods determine if any uncalibrated reference-level pressure estimates associated with an unstable pressure sensor should not be used when calibrating the unstable pressure sensor, and calibrate the unstable pressure sensor using all of the uncalibrated reference-level pressure estimates except any uncalibrated reference-level pressure estimate that should not be used when calibrating the unstable pressure sensor.

Abstract: Determining where to place atmospheric sensors that provide measurements of pressure used to estimate an altitude of a mobile device in an environment. Generally, systems and methods determine where atmospheric sensors can be placed relative to each other in order to achieve a required level of accuracy when an altitude of a mobile device is estimated using pressure measurements from the atmospheric sensors in the network. Particular systems and methods determine a maximum distance for separating adjacent atmospheric sensors, or otherwise determine where to place atmospheric sensors relative to each other based on expected pressure distribution of an environment.

Abstract: Determining when to calibrate a pressure sensor of a mobile device. Particular systems and methods determine values of a plurality of metrics based on how data collected at a first location of a mobile device relates to threshold conditions, determine weights for the metric values, determine weighted metric values by applying the weights to the metric values, use the weighted metric values to determine if a pressure sensor of the mobile device should be calibrated using information associated with the first location, and calibrate the pressure sensor of the mobile device using the information associated with the first location if a determination is made that the pressure sensor of the mobile device should be calibrated using information associated with the first location.

Abstract: Determining whether a mobile device is inside an environment experiencing adverse pressure variation conditions. Particular systems and methods for determining whether a mobile device is inside an environment experiencing adverse pressure variation conditions detect a change in pressure measured by a mobile device that is caused by an HVAC effect of a building or a vehicle, determine a likelihood that the mobile device is inside a building based on an estimated position of the mobile device relative to the building, and determine that the mobile device is inside the building or inside a vehicle based on the likelihood that the mobile device is inside the building.

Abstract: Determining when an estimated altitude of a mobile device can be used for calibration or location determination. Particular systems and methods determine an area in which the mobile device is expected to reside, determine an altitude value of each section of a plurality of sections in the area, determine if the altitude values meet a threshold condition, and determine that the estimated altitude of the mobile device can be used for determining the position of the mobile device or for calibrating a pressure sensor of the mobile device when the altitude values meet the threshold condition.

Abstract: Determining whether a mobile device is inside an environment experiencing adverse pressure variation conditions. Particular systems and methods for determining whether a mobile device is inside an environment experiencing adverse pressure variation conditions detect a change in pressure measured by a mobile device that is caused by an HVAC effect of a building or a vehicle, determine a likelihood that the mobile device is inside a building based on an estimated position of the mobile device relative to the building, and determine that the mobile device is inside the building or inside a vehicle based on the likelihood that the mobile device is inside the building.

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: A receiver capable of receiving and a transmitter capable of transmitting LTE (Long-Term Evolution) signals. The receiver is capable of executing firmware to determine position location from a received LTE-like position waveform over signals modulated on a carrier in a positioning frequency band. In one embodiment the positioning signals are transmitted in a positioning band continuously for up to 100 ms, allowing the receiver to integrate the received positioning signals over a period of up to 100 ms. In one such embodiment, the signals can be integrated coherently for up to 60 ms, assuming acceptable stability of the clock in the receiver and further assuming that less than a predetermined amount of Doppler shift has been introduced in the received signal. The number of physical resource blocks (PRB) can be determined to optimize the signal allocation for the available bandwidth.

Abstract: Generating signals from non-GNSS transmitters, and processing the signals using a GNSS positioning module. Systems and methods identify a chipping rate, identify a PN code length, generate a PN code that has a length equal to the identified PN code length, generate a positioning signal using the identified chipping rate and the generated PN code, and transmit the positioning signal from the transmitter. The PN code length may produce, at the identified chipping rate, a PN code duration that is equal to or is a multiple of a PN code duration used in a GNSS system, the identified chipping rate may be equal to or a multiple of a chipping rate used in a GNSS system, and the identified PN code length may be equal to or a multiple of a PN code length used in a GNSS system.

Abstract: Using atmospheric data from one or more reference nodes to estimate an altitude of a receiver. Assistance data associated with a set of reference nodes within a region is identified, and the assistance data is used to identify atmospheric reference data associated with a subset of selected reference nodes. An estimate of the receiver's altitude is generated using the atmospheric reference data from the subset of reference nodes.

Abstract: Identifying and estimating values of atmospheric conditions for use in estimating an altitude of a mobile device. Systems and methods for monitoring one or more conditions before estimating an altitude of a mobile device may receive a reference pressure that was determined using a measurement of pressure measured by a reference pressure sensor, and determine if a temperature condition is detected. After determining that the temperature condition is not detected, the systems and methods may compute a first estimate of an altitude of a mobile device using the reference pressure.

Abstract: Improving an estimated altitude of a receiver by mitigating the effects of transmitter heating. Systems and methods for improving estimates of a receiver's altitude determine a reference pressure at a reference altitude using a temperature measured at a transmitter or another temperature value, an altitude of the transmitter, and a pressure measured by the transmitter or another pressure value. A local reference pressure for a receiver is determined using the reference pressure and other reference pressures from other transmitters. Reference pressures from overheating transmitters may be weighted less than reference pressures from other transmitters when determining the local reference pressure. The local reference pressure is then used 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: Detecting and mitigating the effects of interference in a positioning system. A received signal is divided into a plurality of receive signal time/frequency (RSTF) values. A plurality of threshold values are determined based on expected energy values for the received signal. In one implementation, if a predetermined number of the RSTF values are above the threshold, the received signal is determined to be corrupt.

Abstract: Estimating a position of a mobile device. Particular systems and methods for estimating a position of a mobile device using information from two positioning technologies determine different position estimates for the mobile device using different positioning technologies, and determine a final position estimate for the mobile device using a weighted combination of the different position estimates. In some implementations, the weighted combination is a weighted average or a weighted median of the different position estimates. Weights may be determined using respective uncertainty metrics corresponding to the respective position estimates.

Abstract: Estimating one or more positions of a receiver using one or more anchor points. Systems and methods for estimating a position of a receiver using a particular anchor point may identify an area of interest that includes anchor points, identify the particular anchor point, and then use information about the particular anchor point to estimate the position of the receiver.

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: Devices, systems, and methods for improving performance in positioning systems. Performance may be improved using disclosed signal processing methods for separating eigenvalues corresponding to noise and eigenvalues corresponding to one or more direct path signal components or multipath signal components.

Abstract: Estimating the position of a receiver using positioning signals and Doppler frequency measurements. Approaches for estimating the position of a receiver using positioning signals and Doppler frequency shift measurements determine an initial estimate of a receiver's position using ranging signals from a first system, generate Doppler frequency shift measurements using the Doppler positioning signals from a second system, and refine the initial estimate using the Doppler frequency shift measurements.