An overview of through the wall surveillance for homeland security

The Air Force Research Laboratory Information Directorate (AFRL/IF), under sponsorship of the Department of Justice's (DOJ), National Institute of Justice (NIJ) Office of Science and Technology (OS&T), is currently developing and evaluating advanced through the wall surveillance (TWS) technologies. These technologies are partitioned into two categories: inexpensive, handheld systems for locating an individual(s) behind a wall or door; and portable, personal computer (PC) based standoff systems to enable the determination of events during critical incident situations. The technologies utilized are primarily focused on active radars operating in the UHF, L, S (ultra wideband (UWB)), X, and Ku bands. The data displayed by these systems is indicative of range (1 dimension), or range and azimuth (2 dimensions) to the moving individuals). This paper highlights the technologies employed in five (5) prototype TWS systems delivered to NIJ and AFRL/IF for test and evaluation