The systems and methods disclosed herein address issues of cost and weight that prevent other threat detection systems intended to detect and identify locations of incoming munitions fire such as RPGs, anti-tank missiles, and other such weapons, from being used more broadly. Systems and methods disclosed herein relate, in part, to a portable, optical sensor that has a 360-degree horizontal field of view and a selectable vertical field of view that can cover up to 90 degrees. Variations of systems and methods discussed herein are meant for use and transport by an individual or group of individuals, and do not require significant support electronics or power supplies in excess of a typical car-battery in size and weight. Other embodiments may be vehicle mounted, or may be further enhanced to work with other detection or response systems.