A survey of early warning technologies

This paper presents a survey of technologies useful in providing early warning in physical security systems. Early warning is important in virtually all types of security systems whether they are used for temporary (tactical, portable, or semi-permanent) applications, border warning, fixed-site detection, or standoff surveillance detection. With the exception of the standoff surveillance detection systems, all systems discussed in this paper usually involve a moving target. The fact that a person(s) to be detected in a standoff surveillance scenario is not moving presents challenging problems and requires different applications of technology. The technologies commonly used to detect moving targets and some suggestions for detection of stationary targets are addressed in this paper