Acoustic Field Fluctuation of Source-Generated Internal Waves and a Robust Detection Method

When a submerged target travels through density-stratified water between bistatic sonar, the source-generated internal waves will disturb the background acoustic channel, making target detection possible. In this paper, three-dimensional amplitude field of source-generated internal wave was constructed based on model of sphere target, and fluctuation of transmission sound field was developed. Characteristics of internal wave on different crossing angles and traveling time were simulated, and the inverse proportional relationship between channel fluctuation and crossing angle was revealed. In order to overcome the overshadow effect of background sound field, a detection method based on empirical orthogonal function was developed to extract the weak distortion characteristics. A lake experiment was conducted to demonstrate the ability.