Remote sensing of personnel badge information using low-cost radar sensors

The authors describe a security surveillance system for monitoring the movement of personnel through halls and passageways while extracting encoded information from badges worn by the personnel passing the monitoring stations. This sensor technology is based on low-cost radar designs similar to the door openers used in many public buildings. The key to this surveillance concept is the badge design that incorporates a small, low-powered digital circuit used to modulate a radar reflector with digitally encoded information. This modulation pattern can be detected at a distance of several feet from the sensor to uniquely identify each badge. Since the radar sensor is also a good motion detector, passage of personnel not having an encoded badge can trigger alarm circuits and activate TV cameras to record the occurrence. They describe the unique monitoring concept, the coded reflector design, potential radar sensor configurations, signal processing algorithms, multiple target separation techniques, and badge coding concepts