[en] Thorough evaluation testing of interior motion sensors requires repeated testing under a variety of environmental conditions. Although the sensors are intended primarily for interior installations, many of the buildings where protection may be required are warehouses or bunkers without environmental control. In evaluating sensors for such installations, it becomes important to collect data not only on coverage or sensitivity at room temperature but also at environmental extremes. This paper describes a system Sandia National Laboratories at Albuquerque (SNLA) has designed and built to provide repeatability in environmental testing. The system has been dubbed Sandia Intruder Motion Simulator (SIMS). This system is used to acquire much of the data now collected on sensors in the laboratory and a duplicate system has been delivered to the Belvoir R and D Center so that the laboratory can now run similar tests. 11 figures