Technology that can determine the source of enemy fire is very useful to rapidly neutralize threats. However, most existing technologies have significant limitations. Acoustic gunshot detection systems are easily confused in multi-path reflection environments, while optical augmentation techniques are not passive and require line of sight to the source. Dismounted marines are currently equipped with various systems to detect small-arms projectiles in flight. These include direct-view visible light and indirect-view image intensification tools, as well as thermal imaging systems operating in infrared imaging bands. The limitation of these systems is that they cannot reliably track to the point of origin. Though solutions based on Mid-Wave Infrared (MWIR) sensors are feasible, they are impractical for widespread use due to cost. IAI will develop SPOTTER, a low-cost Hostile Fire Indicator (HFI) and localization system that can be used by dismounted soldiers during tactical movement. This innovative solution, with the appropriate infrared band sensitivity, is an improved and passive approach for locating the source of hostile, small-arms fire. SPOTTER does not require a direct line of sight to the source of the fire. This system leverages existing low-cost sensors, and augments their capabilities with innovative image processing algorithms to extract the desired information. It is a man-portable, battery-powered, standalone, small-arms fire location system. SPOTTER not only helps to detect and neutralize threats rapidly, but also eliminates immediate, accurate return fire by forcing the enemy to shoot from increasingly difficult positions.