Patent attributes
An entry portal to a facility includes magnets to produce a magnetic field and a proximity sensor to detect passage of a user. A portable device carried by a user detects the magnetic field and generates magnetometer data which is then sent to the portal along with a device identifier. The magnetometer data is compared to expected magnetic field data to determine presence at the portal. Timestamps of the magnetometer data and data from the proximity sensor may be compared to determine whether the two events occurred contemporaneously. If so, the portable device is deemed to be present at the portal. The device identifier may be used to determine a user, and entry data indicative of entry of the user may be generated. Subsequently, the user may then be tracked using sensors in the facility.
