Transcript Slide 1
Long Fiber-Optic Perimeter Sensor: Intrusion Detection W. Tim Snider, Faculty Advisor: Dr. Christi K. Madsen Texas A&M Department of Electrical and Computer Engineering Introduction Intrusion Detection Security systems are widely used in today’s world, and the goal with them is to detect unwanted intruders. Traditional perimeter systems tend to have limited range. Such systems includes seismic sensors, cameras, motion detectors, and fences. These are generally above ground and can be seen, thus giving the intruder a chance of avoiding detection. At places like nuclear power plants, embassies, military bases, and borders, perimeters could stretch for miles, proving to be costly. Not only would large perimeters be costly, but as the distance increases, you are also increasing the number of components. This adds to the complexity of the system, along with the chance of failure. In looking for a system that is covert, cheap, and large scale, fiber-optic technology provides an option. The developed program triggers a pulse to be introduced into the buried fiber with a 2us width and 150us period. An intruder stepping over (or near) the buried optical cable results in a phase perturbation. This causes an amplitude change in the Rayleigh backscattered wave. The program also continuously monitors two channels in real-time with data acquisition at 2 MHz. The Rayleigh backscattered signal is detected by Dr. Madsen’s sensing equipment with analog outputs, and an ADC is used to connect to the FPGA board. Results Using NI LabVIEW and the FPGA module, a program was developed that successfully monitors the perimeter sensor for intrusions. The program has the following specifications: • Data acquisition at 2MHz • Filtering performed on the FPGA • Intrusions triggered by a set threshold value • Maintains a 10 second buffer of data • Generates timestamped 60 second intrusion data files • Saves raw data along with filtered data for both channels Future Additions The FPGA then filters the incoming signal, and for each channel compares the filtered value to a preset threshold value. If the value is larger than the threshold on either channel, an intrusion is triggered. Project Outline This project expands on Dr. Christi Madsen’s fiber-optic intrusion system research. Telecommunications-grade optical fiber is buried approximately one foot in the ground, with a laser and sensing equipment located in a control room. The goal of this project is to create a program using NI LabVIEW and a FPGA Module that will monitor the fiber-optic intrusion system with the following specifications: A 10 second buffer of raw and filtered data is constantly maintained. Once an intrusion is triggered, this buffer along with 50 seconds of real time intrusion data is stored in a text file. A separate program can then be used to plot and analyze the intrusion data. Possible improvements for the detection program include: • Using digital ports instead of digital lines on the FPGA input • Different algorithm to determine intrusions using both channels • Intrusion triggering without delay Conclusion System Testing The developed program monitors the perimeter sensor in real-time and detects intrusions. The only specified requirement that was not met is the data acquisition rate. However, the 150us period was maintained, so it does not detract from the ability to detect intrusions. • Acquire data at 5MHz on two channels • Filter the data (on the FPGA) • Analyze the data for an intrusion • Save data when there has been an intrusion Equipment Used A new laser was recently obtained with the goal of increasing sensitivity and minimizing the detection of acoustic noise inside the control room. As of the end of the REU program, the intrusion system was still being adjusted to work with the new laser. Riverside Campus Test Site, Bryan, TX • NI FPGA Fiber-optics provides a feasible solution for the creation of a covert and cost-effective perimeter sensor. Such a system could be utilized at many locations throughout the world. Successful field testing shows that this technology could soon be ready for commercialization. • PCI – 7831R • A/D Converter • Fall 2006 Senior Design Group • Sensing Equipment • Provided by Dr. Christi Madsen Extracted Footsteps Triggered Intrusion This project part of the 2007 Research Experience for Undergraduates (REU) – Electrical Engineering Research Applications to Homeland Security, and is funded by grants from the National Science Foundation (NSF) and Department of Defense (DOD). Special thanks to Dr. Christi K. Madsen for her guidance, J. Paul Chambers for his help, and NI Applications Engineers Tunde Azeez, Craig Davis, and Matthew Pollock.