Shooter Localization using a Wireless Sensor Network of Soldier-Worn Gunfire Detection Systems

Highly accurate small-arms gunfire detection systems on individual soldiers are vital requirement for added battlefield situational awareness and threat assessment. Today, several acoustic shooter localization systems are commercially available [2, 7, 29]; an overview of such systems can be found in [26]. A few examples of soldier-wearable shooter localization systems include the Shoulder-Worn Acoustic Targeting System (SWATS) by QinetiQ North America, Inc., Boomerang Warrior-X by BBN Technologies, and PinPoint by BioMimetic Systems. These Soldier-wearable Gunfire Detection Systems (SW-GDSs) can provide a good level of localization accuracy as long as the soldier is at an ideal location relative to the shooter and the bullet trajectory. However, due to the dissipative nature of acoustic signals, localization systems suffer severe performance degradation as the distance to the shooter and the bullet trajectory increases [22, 23, 28]. Moreover, when a relative solution, i.e., the shooter location relative to the sensor, is transformed into a georectified solution using a magnetometer and GPS, the solution often becomes unusable due to localization errors. Geo-rectified solutions are necessary when displaying hostile fire icons on a Command and Control Geographic Information System (C2 GIS) map display. SW-GDSs use acoustic phenomena analysis of small-arms fire to localize the source of incoming fire, usually with a bearing and range relative to the user [12]. Currently, the individual SW-GDSs operate separately and are not designed to exploit the sensor network layout of all the soldiers within a Small Combat Unit (SCU) to help increase accuracy. Researchers are exploring some novel solutions that utilize the team aspect of these SCUs by exploiting all SW-GDSs in a squad/platoon to increase detection rates and localization accuracy [9, 10, 32]. Apart from soldier-wearable systems, there exist several single-microphone as well as microphone array-based sensor network approaches to shooter localization [6, 15, 16, 19, 24]. Most of the existing sensor fusion schemes for shooter localization are centralized approaches where the individual sensor measurements, such as time of arrival or angle of arrival of the muzzle blast or the shockwave are combined to yield a single estimate of the shooter position [5, 16, 19, 20, 32]. Here we consider a hierarchical approach where the relative shooter position from the individual sensors are fused to obtain a more accurate geo-rectified shooter position. The proposed approach takes full advantage of the team aspect of a SCU to provide a fused solution that would be more accurate and suitable for a C2 GIS map display than the individual soldier’s solution. The objective here is to improve accuracy across an entire SCU so even soldiers in non-ideal settings (out of range, bad angle, etc.) can exploit the good solutions