US Patent 8378815 Asset tracking with error adaptive boundary

Systems and methods for tracking assets from central stations using tracking devices enabled to receive GPS coordinates or site identities broadcast from transmitters at fixed locations within a wireless network. Plural position fixes are taken over time and forwarded to the central station. The position fixes are compared to establish a likelihood that apparent excursions from a predetermined boundary area are valid or not, prior to generating an alert signal that the asset has moved from the boundary area.