Evolution of the Army Research Laboratory Ultra-Wideband Test Bed

For over 20 years, the US Department of Defense has recognized the need and has applied resources to develop systems to find targets in foliage. In large measure these early efforts were disappointing because of the lack of appropriate technologies. Recent developments in Analog-to-Digital (A/D) converter technology, source technology, and signal processing power have presented new opportunities in this area. The Army Research Laboratory (ARL) began a research program to determine the feasibility of bringing these emerging technologies together to analyze the problem of seeing through an inhomogenous medium. The results of these studies indicated that continuing work in this area and sponsoring enabling technologies could produce a realizeable system. Thus, ARL is presently engaged in the Ultra Wide Band (UWB) Foliage Penetration (FOPEN) Synthetic Aperture Radar (SAR) program to support this work. The particular implementation ARL is pursuing in UWB is an impulse (very short pulse) approach. This is an exploratory development program aimed at measuring and analyzing the basic phenomenology of impulse radar and the propagation effects of targets, clutter, and targets embedded in clutter. Past efforts have fallen short in that they have failed to detect targets with a probability of detection (Pd) and probability of false alarm (Pfg) that were useful for military applications. In order to obtain acceptable Pd and Pfa levels, real target and clutter statistics must be collected, and specific detection logic must be developed. To this end, ARL has developed a testbed facility to allow the collection of repeatable data at the Adelphi, MD, site.