Distributed sensing in homeland security applications

The paper deals with the implementation of a suitable technological support to improve the success likelihood of Urban Search and Rescue (USAR) missions. In particular, the adoption of an heterogeneous sensors network for situation awareness and security applications is suggested. The sensor network consists of two types of sensor, mandated, respectively, to through-the-wall radar (TTW) imaging and a vital sign detection (VSD) sensor. Information and measurement data collected by the network are sent to a command and control center for optimal decision making. More specifically, after a brief introduction about the considered network architecture and the TTW radar, the authors present hereinafter a new measurement method, based on Doppler effect and eigenvalue decomposition, for VSD. In particular, thanks to the application of a preliminary demodulation scheme to the received measurement signal, the method is capable of detecting and measuring the phase modulation associated human chest movement. A number of tests, both in simulated and actual measurement conditions, has highlighted satisfying performance in terms of accuracy and reliability, thus suggesting the method as an ideal candidate for the implementation of the VSD sensor.