1. Field of the Invention
The present invention generally relates to target tracking and engagement techniques for achieving accurate launching of a submunition and, more particularly, is concerned with a target tracking system for determining the bearing to a ground object emitting acoustic energy.
2. Description of the Prior Art
A wide area mine (WAM) submunition is currently being developed for the U.S. military. The WAM (also termed a "smart" mine) submunition basically includes a noise sensor that can detect sounds, or an acoustic signature, of a moving target, a launcher tube containing a sublet, a positioning mechanism for aiming the launcher tube, and an arming and firing mechanism for launching the sublet from the launcher tube.
The WAM submunition is initially deployed in a target area in a laid down position on the ground. A self-righting mechanism of the WAM submunition is used to erect the launcher tube from the laid down position to an upright position prior to final arming. After erecting the launcher tube, the self-righting mechanism stabilizes the submunition in the upright position while maintaining it coupled with the ground. The positioning mechanism then aims the launcher tube toward the target so that the sublet when fired will be launched over the target.
For the sublet to be successfully launched over the target, tracking and engagement techniques must be available that are capable of determining the bearing to the sensed target and range of the target in the first place so that proper aiming of the launcher tube and launching of the sublet can be achieved. To be effective such tracking and engagement techniques must demonstrate a high degree of accuracy, have sufficient range and be capable of operating in a wide variety of environmental and site conditions.
Heretofore, analog tracking techniques have been employed that use small microphone arrays for sensing the acoustic signature. These techniques have tracking ranges limited to less than 100 meters and are subject to a significant degree of tracking errors.
Digital tracking techniques that have been employed heretofore involve cross-correlation and beam-forming operations. These techniques require more processing capability in the system and/or very large array sizes in order to achieve a satisfactory level of accuracy and range.
Consequently, a need remains for improvements in tracking and engagement techniques for determining the bearing and range of a ground target in order to accurately aim a submunition toward the target at significant range.