Year
1994
Abstract
A paper presented by the author at the 1993 INMM annual meeting described a study which compared the suitability of five different surface types (sand, asphalt, grass, concrete and gravel) as backgrounds for a passive thermal infrared intrusion detection system (IDS). Experimental surface temperature and meteorological data recorded during July 92 at a test site in New Hampshire were utilized in the study as well as models for predicting intruder surface temperature and infrared IDS performance. For the period investigated, the predicted number of \"missed\" intruder crossings was lowest for the gravel surface. This raised the question as to whether gravel backgrounds are preferable, in general, for such an IDS application. A follow-up investigation was initiated at a test site in Vermont to address this issue. This study is examining the thermal behavior of a gravel bed and how it influences both the nuisance alarm rate and the intruder detection capability of an infrared IDS. Experimental results from last August for this gravel bed and an adjacent grassy area are presented in this paper. A simple model is also described which is used to examine the influence of gravel aggregate size, vegetative and structural \"clutter\" and wind speed on gravel surface temperatures.