Blog Date: 4/18/2012
Author: Ray Coulombe

From the first time I used a Hertz GPS navigation system in lieu of a paper map on the front passenger’s seat, I have found the technology to be an almost indispensable tool. Its adoption over the last 10 years has been remarkable and, for many, a must-have feature in cars and phones. Not surprisingly, GPS has security applications — and vulnerabilities. GPS is a satellite-based navigation system made up of a network of 24 satellites circling the earth twice daily at about 12,600 miles altitude. GPS satellites transmit 50-watt signals (@ 1575.42 MHz in the UHF band for civilian use) which GPS receivers use to determine time of transmission and, using the signal speed (nearly the 186,000 miles per second speed of light), calculate a distance to each one seen. With three satellites in view, latitude and longitude (2-D) can be derived; and altitude can be calculated (3-D) when four or more satellites are visible. Many GPS units show derived information such as direction and speed, calculated from position changes.
GPS has been used in security to provide monitoring and security of people and assets. Cellular (GSM, GPRS, CDMA), satellite radio (SATCOM), text (SMS) and e-mail are commonly used to send real-time position data and, in some products, device information including system health and status and alarm information. Some manufacturers also employ short and long-range FM radio transmission. Alternatively, data may be stored on a device local to the GPS receiver for later analysis.
Applications include personnel tracking and safety, vehicle tracking, fleet management, container and trailer monitoring, taxi management, ATM tracking, school buses, oil-tank truck monitoring, police patrol management and ambulance management. An interesting variation is “geo-fencing,” where a virtual perimeter is established using coordinate information, allowing the determination of when a person or object has crossed the boundary. With the growing use of smart phones as portals, data repositories and authentication devices for security systems, techniques for locating and recovering lost or stolen devices — such as Apple’s “Find My iPhone” — take on additional importance.
Link to Complete Article as it appeared in Security Technology Executive Magazine

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