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 one or more heights of one or more mobile devices above surfaces. Particular embodiments described herein include machines that retrieve first data (e.g., measurement value(s) determined by sensor(s) of a mobile device or estimated position(s) of the mobile device), determine a location context based on the first data, identify second data (e.g., measurement value(s) determined by sensor(s) of the mobile device or status indicator value(s) of feature(s) of the mobile device) to retrieve for use in determining an estimated height above a surface at which the mobile device is located based on the determined location context, retrieve the second data, and determine an estimated height above a surface at which the mobile device is located based on the retrieved second data.

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: Determining one or more heights of one or more mobile devices above surfaces. Particular embodiments described herein include machines that retrieve first data (e.g., measurement value(s) determined by sensor(s) of a mobile device or estimated position(s) of the mobile device), determine a location context based on the first data, identify second data (e.g., measurement value(s) determined by sensor(s) of the mobile device or status indicator value(s) of feature(s) of the mobile device) to retrieve for use in determining an estimated height above a surface at which the mobile device is located based on the determined location context, retrieve the second data, and determine an estimated height above a surface at which the mobile device is located based on the retrieved second data.

Abstract: Determining if a receiver is inside or outside a building or area. Particular systems and methods for determining if a receiver is inside or outside a building determine an estimate of a position of a receiver, and use the estimate of the position of the receiver and other data to determine if the position of the receiver is inside a first building. The other data may include locations of geo-fences inside buildings, heights of buildings, or other types of data.

Abstract: Determining one or more heights of one or more mobile devices above surfaces. Particular embodiments described herein include machines that retrieve first data (e.g., measurement value(s) determined by sensor(s) of a mobile device or estimated position(s) of the mobile device), determine a location context based on the first data, identify second data (e.g., measurement value(s) determined by sensor(s) of the mobile device or status indicator value(s) of feature(s) of the mobile device) to retrieve for use in determining an estimated height above a surface at which the mobile device is located based on the determined location context, retrieve the second data, and determine an estimated height above a surface at which the mobile device is located based on the retrieved second data.

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 computed using a measurement of pressure from a first reference pressure sensor at a first location, wherein the received reference pressure specifies an estimated pressure for a reference altitude, and determine if a threshold change in measured pressure by the first reference pressure sensor is detected. If the threshold change in measured pressure is detected, the systems and methods may compute a calibration value for the first reference pressure sensor, or if the threshold change in measured pressure is not detected, the systems and methods may identify a previously-determined calibration value.

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: Determining an altitude error value associated with an estimated altitude of a mobile device. In certain disclosed systems and methods for determining an altitude error value associated with an estimated altitude of a mobile device, a first error value related to systematic error and a second error value related to statistical error are determined, and the altitude error value is determined using the first error value and the second error value.

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: Pressure-based estimation of a mobile device altitude or calibration of a pressure sensor. Particular embodiments described herein include machines that determine if a reference-level pressure value based on one or more measurements of pressure from a network of weather stations should or should not be used to calibrate a pressure sensor of a mobile device or to estimate an altitude of the mobile device. If a first determination is made that the reference-level pressure value should be used, the reference-level pressure value is used to calibrate a pressure sensor of a mobile device or to estimate an altitude of the mobile device.

Abstract: Estimating range bias in a timing-based radio positioning network. Systems and methods estimate range bias, and use the estimated bias to adjust an estimated range measurement for use in estimating a position of a receiver. Estimated range bias may be based on surveyed range errors associated with locations near the position of the receiver, or may alternatively be based on comparisons of different range measurements.

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: 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: Determining an indoor or outdoor location of a mobile device. Particular embodiments described herein determine a geographic area of potential locations in which a mobile device resides, identify any buildings that occupy part of the geographic area, and determine if the mobile device does not reside inside any building, the mobile device resides inside a particular building from the identified buildings, or that one or more of the identified buildings are candidate buildings in which the mobile device may reside based on the geographic area and building footprints of the identified buildings.

Abstract: Extending the spatial coverage of a reference pressure network. Particular embodiments described herein include machines that initially determine that an estimated position of a mobile device resides outside a coverage area of a network of reference pressure sensors. Reference-level pressures corresponding to reference pressure sensors of the network are determined using measurements of pressure from the network of reference pressure sensors. A pressure pattern for a region that includes the estimated position and an area not included in the coverage area of the network is determined using reference-level pressures that were not determined using measurements of pressure from the network of reference pressure sensors. The reference-level pressures corresponding to reference pressure sensors of the network and the pressure pattern are used to determine a reference-level pressure value for use in calibrating a pressure sensor of the mobile device or for use in estimating an altitude of the mobile device.

Abstract: Estimating a difference in height between two floors in a building for use in estimating a height or an altitude of one of the two floors. Particular embodiments estimate a height difference between a first floor and a second floor based on a first outdoor temperature of a first time period, a second outdoor temperature of a second time period, a third temperature that is based on an indoor temperature of the first time period or the second time period, a first estimated difference in height between the first and second floors that is based on measurements of pressure from mobile devices when those mobile devices were on the first and second floors during the first time period, and a second estimated difference in height between the first and second floors that is based on measurements of pressure from mobile devices when those mobile devices were on the first and second floors during the second time period.

Abstract: Determining an indoor or outdoor location of a mobile device. Particular embodiments described herein determine a geographic area of potential locations in which a mobile device resides, identify any buildings that occupy part of the geographic area, and determine if the mobile device does not reside inside any building, the mobile device resides inside a particular building from the identified buildings, or that one or more of the identified buildings are candidate buildings in which the mobile device may reside based on the geographic area and building footprints of the identified buildings.

Abstract: Using a calibration sensor to calibrate an unstable sensor from a network of unstable sensors. Approaches for using a calibration sensor to calibrate the unstable sensor initially identify an unstable sensor in a geographic region to be calibrated by a calibration sensor using a model of environmental conditions for the geographic region, and then use the model to determine how to calibrate the unstable sensor using the calibration sensor.

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.