An all-directional interference cancelling system for large sonar array

The exsistence of strong mterfernces is the main constraint factor, which influences the performance of a mid-or long-range sonar. For a sonar with large array, the problem of anti-interferences in all-direction has not been solved yet due to the requirements of over-long time dieay line and the over-high input-output rate. A method is proposed in this paper, which can be used in the sonar design with large array for supressing t e strong interferences in all direction. This is a combined architecture of adaptive noise canceller and a programmable DICANNE system proposed by V. C. Anderson. In the case that the incidental angle between signal and intefrence is small, the adaptive noise canceller will be adopted in a relative low sampling frequency. In the case that the incidental angle between signal and interference is large, the programmable DICANNE will work in the high sampling frequency so that the overall system has the ability of canceling strong interferences from all directions. The structure described in this paper is easy to implement in hardware by using the DSP chips. The block diagram of the combined system and the design idea are presented.