Technology Of Tracking
Global Positioning System (GPS) and related technologies are being developed and employed to monitor the location of people, vehicles, and objects, with their accuracy and applicability determined by the technologies’ limitations. The satellite-based GPS navigation system, which can triangulate a user’s precise whereabouts within meters of accuracy, cannot function indoors, while Garmin International’s Ted Gartner notes that a typical GPS receiver cannot be used as a tracking device because it does not transmit data.
University of Maryland College Park researchers employ an alternative approach with Horus, a navigational and positioning system that uses wireless fidelity (Wi-Fi) access points to facilitate indoor tracking. “Horus measures the signal’s strength that it’s getting from the access points in an area and, based on that, determines its location,” explains system developer and professor Ashok Agrawala, director of the Institute for Advanced Computer Studies’ Maryland Information and Network Dynamics (MIND) Lab.
Agrawala is also developing another system, Pinpoint, that uses portable access points to track people and objects in areas without Wi-Fi. The nodes will broadcast signals back and forth and to another node affixed to the object or person to be monitored, using the distance measured to ascertain location.
GPS receivers can help track people and vehicles when they are integrated with transmitters; one such deployment is a Nextel Communications system for tracking 1,300 school buses in the Prince George’s County School District through the use of built-in GPS-enabled cell phones that monitor each bus’ location and speed and transmit that data to the transportation department in real time.
GPS is also being used by the Virginia Cooperative Extension office in Arlington County to map diverse species of invasive plants.
Abstracted by the National Law Enforcement and Corrections Technology Center(NLECTC) from the Washington Times (03/10/05) P. B1; Widhalm, Shelley .