Geolocation of an Audio Source in a Multipath Environment Using Time-Of-Arrival

The Air Force and the Department of Defense (DoD) are continually searching for ways to protect U.S. forces, both stateside and abroad. One continuing threat, especially in the current world environment, is gunfire from an unseen sniper. Designated areas, such as a forward deployed base or motorcade route, need to be continuously monitored for sniper fire. Once detected, these gunmen need to be located in real time. One possible method for accomplishing this task is to geolocate the audio signals generated using time-of-arrival (TOA) algorithms. These algorithms rely on direct-path measurements for accuracy. Multipath environments therefore pose a problem when measuring signals from the audio spectrum. The errors induced by a multipath environment can be reduced by introducing additional audio receivers to the detection system. By sampling all possible combinations of a minimum set of receivers (four), a more accurate location can be calculated. An accuracy of six meters can be achieved roughly 69 percent of the time, though most of the error occurs in the vertical component. An accuracy of six meters in the X/Y plane can be achieved approximately 97 percent of the time.