Intelligent Recognition of Acoustic and Vibration Threats for Security Breach Detection, Close Proximity Danger Identification, and Perimeter Protection1

The protection of perimeters in national, agricultural, airport, prison, and military sites, and residential areas against dangerous approaching human and vehicles when using human agents to provide security is expensive or unsafe. Because of this, acoustic/vibration signature identification of approaching human and vehicles threats has attracted increased attention. This paper addresses the development and deployment of three types of acoustic and vibration based smart sensors to identify and report sequential approaching threats prior to the intrusion. More specifically, we have developed: a) acoustic based long range sensor with which vehicles' engine sound and type can be identified, b) vibration based seismic analyzer which discriminates between human footsteps and other seismic events such as those caused by animals, and c) fence breaching vibration sensor which can detect intentional disturbances on the fence and discriminate between climb, kick, rattle, and lean. All of these sensors were designed with several issues in mind, namely, optimized low power usage, a low number of false positives, small size, secure radio communication, and milspec. The developed vibration based system was installed in an airport with unprotected shore lines in the vicinity of taxiand run-ways. The system reported an average of less than two false positives per week and zero false negative for the duration of forty-five days. Six fence sensors were installed on the terminal area and end-ofrunway chain-link fences where there was possibility of intentional fence climbing. The fence sensors reported no false positives for the duration of forty-five days which included several days of seasonal storms. INTRODUCTION The increasing emphasis on perimeter protection of national assets, both at home and abroad, has spurred the development of technologies that can detect potential threats, such as humans or approaching vehicles. One area of interest is the combination of several different sensors, each with their own distinct modalities and detection ranges, to create a versatile and robust system. We propose a system that would be based on three security sensors which have been demonstrated to provide detection and classification of security threats. These sensor types are acoustic, seismic, and vibration sensors. The "Smart Fence" system based on these sensors would be particularly suited for the identification and reporting of sequential approaching events, such as an approaching vehicle with passengers desiring to breach a fenced facility. One benefit is that the likelihood of detection of intruders is increased because the sensors are designed for detection of different characteristics of an intrusion attempt. For example, if one sensor misses detection due to some confounding event, other sensors may not be susceptible to such an event, providing another chance for detection. Another benefit is that the sensors allow the system to deliver threatlevel information about incoming threats. For example, vehicles detected at a long distance may have a lower threat-level than intruders approaching a secure perimeter, which in turn may have a lower threat level than the intruders attempting to scale a fence surrounding the perimeter. The acoustic signatures of interest generated by approaching human and running vehicles are complicated. In the case HOMELAND SECURITY AFFAIRS, SUPPLEMENT 3 (MARCH 2011) WWW.HSAJ.ORG Report Documentation Page Form Approved