Abstract:
Surveying techniques for generating location fingerprint data are described. A mobile device can survey a venue by measuring, at multiple locations at the venue, signals from one or more signal sources. At each location, the mobile device can take multiple measurements of signals. The mobile device can take each measurement at a distinct orientation. The measurements can be used to determine expected measurements of the signals at the venue. Differences between the multiple measurements of signals can be used to determine a variance of the expected measurements. The expected measurements and variance can be designated as location fingerprint data for the venue. The location fingerprint data can be used by mobile devices for determining a location at the venue.
Abstract:
A proximity fence can be a location-agnostic fence defined by signal sources having no geographic location information. The proximity fence can correspond to a group of signal sources instead of a point location fixed to latitude and longitude coordinates. A signal source can be a radio frequency (RF) transmitter broadcasting a beacon signal. The beacon signal can include a payload that includes an identifier indicating a category to which the signal source belongs, and one or more labels indicating one or more subcategories to which the signal source belongs. The proximity fence defined by the group of signal sources can trigger different functions of application programs associated with the proximity fence on a mobile device, when the mobile device moves within the proximity fence and enters and exits different parts of the proximity fence corresponding to the different subcategories.
Abstract:
Survey data for an environment is used to predict the accuracy of a position estimate in the environment and whether or not more survey data may improve that accuracy. In some implementations, a user performs a site survey of an environment by observing the strengths of radio frequency signals at various survey points in the environment. An expected positioning accuracy of the surveyed environment can be determined using the new survey data collected and optionally historical survey data for the environment. The user can be informed about the usefulness of collecting additional survey data and/or the expected positioning accuracy in the environment.
Abstract:
Among other things, we describe a method that includes receiving, on a mobile device, an indication that an application executing on the mobile device has entered a background state, receiving, from the application, a value indicating a condition for providing location data to the application, disabling a resource associated with the application, while the resource associated with the application is disabled, storing location data received from a location system of the mobile device, and when the condition indicated by the value is met, enabling the resource associated with the application, and providing the stored location data to the application.
Abstract:
Surveying techniques for generating location fingerprint data are described. A mobile device can survey a venue by measuring, at multiple locations at the venue, signals from one or more signal sources. At each location, the mobile device can take multiple measurements of signals. The mobile device can take each measurement at a distinct orientation. The measurements can be used to determine expected measurements of the signals at the venue. Differences between the multiple measurements of signals can be used to determine a variance of the expected measurements. The expected measurements and variance can be designated as location fingerprint data for the venue. The location fingerprint data can be used by mobile devices for determining a location at the venue.
Abstract:
Methods, program products, and systems for reducing a location search space are described. A mobile device, when arriving at a venue, can determine a location of the mobile device using signals from one or more signal sources associated with the venue. The mobile device can use a coarse location estimator to estimate a coarse location of the mobile device at the venue. The mobile device can request, from a server, detailed location data associated with the coarse location. The detailed location data can include location fingerprint data associated with a portion of the venue that includes the coarse location. The mobile device can determine an estimated location that has finer granularity than the coarse location using the location fingerprint data.
Abstract:
A mobile device can be in multiple states of location determination. In each state, the mobile device can use a distinct subsystem to determine a location. A state machine of the mobile device can manage the states, including determining which state the mobile device is in and whether a transition between the states has occurred. A transition can be triggered by a sensor of the mobile device and confirmed by another sensor of the mobile device. When the state machine detects a transition, the mobile device can switch location determination from one subsystem to another subsystem, and change a map user interface to one that is best suited for the new subsystem.
Abstract:
Systems, methods, and computer program products for determining the location and direction of travel of a mobile device using map vector constraints is disclosed.
Abstract:
A parameter related to the Earth's magnetic field can be used to determine accuracy of a magnetometer of a mobile device. In one aspect, a first instance of a parameter related to Earth's magnetic field is determined using data generated by the magnetometer. The magnetometer data can be based in part on a position of the mobile device with respect to the Earth. A second instance of the parameter can be determined using data generated by a model of Earth's magnetic field. The model data can also be based in part on the position of the mobile device with respect to the Earth. The first instance of the parameter can be compared with the second instance of the parameter. An accuracy metric for the magnetometer can be determined based on a result of the comparison. An indication of the accuracy metric can be presented by the mobile device.
Abstract:
Methods, program products, and systems for using multiple sensors to determine a location fingerprint are described. A sampling device can measure RF signals detected at a train station of a transit system or a route of the transit system. The sampling device, or a location server receiving the measurements, can filter RF signal measurements using one or more readings from sensors coupled to the sampling device and that are different from RF receivers. The readings can be taken concurrently with the RF signal measurements. These readings, designated as motion cues, can include motion sensor readings, barometer readings, or magnetometer readings. Using the motion cues, the sampling device or location server can distinguish different platforms of a station of the transit system and different levels of the station, or filter out RF signal measurements that may have been inaccurate, e.g., as caused by disturbances from a train entering or leaving a station.