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Method and apparatus for active tamper indicating device using optical time-domain reflectometry

United States Patent

December 14, 1999
View the Complete Patent at the US Patent & Trademark Office
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An optical time-domain reflectometer (OTDR) launches pulses of light into a link or a system of multiplexed links and records the waveform of pulses reflected by the seals in the link(s). If a seal is opened, the link of cables will become a discontinuous transmitter of the light pulses and the OTDR can immediately detect that a seal has been opened. By analyzing the waveform, the OTDR can also quickly determine which seal(s) were opened. In this way the invention functions as a system of active seals. The invention is intended for applications that require long-term surveillance of a large number of closures. It provides immediate tamper detection, allows for periodic access to secured closures, and can be configured for many different distributions of closures. It can monitor closures in indoor and outdoor locations and it can monitor containers or groups of containers located many kilometers apart.
Smith; D. Barton (Oak Ridge, TN), Muhs; Jeffrey D. (Lenoir City, TN), Pickett; Chris A. (Clinton, TN), Earl; D. Duncan (Knoxville, TX)
Lockheed Martin Energy Research Corp. (Oak Ridge, TN)
08/ 885,972
June 30, 1997
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT This invention was made with United States government support awarded by the United States Department of Energy under contract to Lockheed Martin Energy Research Corporation. The United States has certain rights in this invention.