Radio Frequency (RF) Detection of Small Arms Fire, 10-R8173
Principal Investigators
Thomas C. Untermeyer
Gregory C. Willden
Carl E. Weiss
Andrew R. Cormier
Chuong D. Khuc
Inclusive Dates: 07/01/10 – 12/31/11
Background — For defense purposes, the military has an interest in detecting weapons as soon as possible after their firing or launching from as far away as possible. Optical, infrared (IR), and acoustic systems exist today that can detect the firing of a variety of weapons. However, these detection methods do not work as well during obscured environmental conditions caused by phenomena such as clouds, fog and rain. Acoustic systems also provide much slower response time and limited range. Since the 1950s, the open literature has reported the possible generation of radio frequency (RF) emissions caused by the launching of a variety of weapons. Passive RF detection of weapon launches could provide a benefit over optical, IR and acoustic systems by providing fast detection through obscured environments over extended ranges.
Approach — Using lessons learned during previous testing, including developing sensors used to collect RF data from a variety of weapons, the objective of this internal research project was to reliably and consistently detect the RF signals caused by the firing of automatic weapons at a distance of over one-quarter mile (400 meters) and to understand the phenomenology associated with the cause of the RF signal.
Accomplishments — The team developed a test plan and assembled the appropriate antennas and test equipment to collect RF and video data at the SwRI ballistics outdoor range and in an SwRI indoor shielded enclosure during the firing of a small arms automatic weapon. Although the team did capture valid RF signals again during the testing performed, the signals did not occur every time, and the signals did not provide an adequate signature to differentiate them from other external transmitters.
Consequently, for the particular automatic weapon and the particular test equipment used, this internal research did not reveal the presence of the necessary RF signatures for detection of the firing of weapons at a useable distance. Although this latest research did not reveal sufficient RF signal detection, further research using a different approach or using different test setups could still potentially reveal a solution for achieving positive identification of the firing of automatic weapons at practical distances. This conclusion is based on the following facts:
- Testing has shown that during the firing of an automatic weapon, the barrel and the bullet develop significant voltages that can serve as a power source for subsequent high-speed discharges.
- Testing has shown that the firing of a weapon does produce RF signals of sufficient strength for detection at adequate standoff distances.
- Testing has not shown that the detected RF signals have a unique signature.
- Testing has not determined the precise phenomenology associated with the RF signal generation.
