Abstract: Calibrating an unstable sensor of a mobile device. Systems and methods for calibrating a sensor of a mobile device determine a first estimated position of the mobile device without using any measurement from the sensor of the mobile device, generate a second estimated position of the mobile device using a measurement from the sensor, estimate a sensor error of the sensor using the first estimated position and the second estimated position, and use the sensor error to determine a calibration value for adjusting one or more measurements from the sensor.

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: Calibrating an unstable sensor of a mobile device. Systems and methods for calibrating a sensor of a mobile device determine a first estimated position of the mobile device without using any measurement from the sensor of the mobile device, generate a second estimated position of the mobile device using a measurement from the sensor, estimate a sensor error of the sensor using the first estimated position and the second estimated position, and use the sensor error to determine a calibration value for adjusting one or more measurements from the sensor.

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 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 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: 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: 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: 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: Determining building weather profile parameters, and correcting an estimated altitude of a receiver using the building weather profile parameters. Systems and methods for estimating an altitude of a receiver using building weather profile parameters may identify one or more weather profile parameters for a building, determine an initial estimate of a receiver's altitude at a floor inside the building, and use the initial estimate and the identified weather profile parameters to determine a corrected estimate of the receiver's altitude at the floor.

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.