Directed Method Of Low-altitude Targets Sound

In recent years, acoustic detection become an important approach to combat moving targets in a battle field. Due to a lower cost in calculation and a higher accuracy, TDE (Time Delay Estimation) theories become quite generally used in acoustic detection. It has taken the scientists world wide working on it for more than 30 years. In a battle field, an investigation in a multiple-target problem makes much sense.A discussion of several typical acoustic sources involved in acoustic detection problem is presented. The generation and frequency domain characteristics are discussed detailedly. An analysis over sound propagation in a very low altitude is available in this paper, in which a discussion over how temperature, humidity, wind and rain affect an acoustic detection is presented.In this paper, some experiments are done to test the typical TDE theories, which are fatal to the detection and bearing estimation. Quite a few TDE approaches are presented in detail. They are discussed and compared with each other. The general correlation TDE approach is mainly investigated in the paper.A 4-element small acoustic detection cross array is presented geometrically and mathematically .Then, a discussion over how the approaches based on TDE theories work is available, which is the point of this paper. The TDE approach is examined under a 2-target situation. The TDE approach is tested by comparing the estimation position and the actual position with different target parameters.The last but not the least, a brand new approach is presented. In this approach, we use some time delay compensation and bearing scanning to get the bearing estimation of the target. The theories over how the approach works are detailedly presented. Some experiments are done to test this approach under one-target and two-target situations.