Title: Application of the direct blast adaptive suppression method to the forward cattered broadband signals

Author: HE Chuanlin; YANG Kunde; MA Yuanliang; LEI Bo

Affiliation: Key Laboratory of Ocean Acoustics and Sensing (Northwestern Polytechnical University), Ministry of Industry and Information Technology, et al.

Abstract: The basic principles of target detection by forward acoustic scattering are presented. A direct blast suppression approach based on adaptive filtering (DBS-AF) is proposed to suppress the direct blast. The DBS-AF technique is extended to the linear frequency modulation (LFM) signal, where the envelope of the signal is regarded as a ``general waveform'' and imported into the adaptive filter. Application of the DBS-AF method to the data collected from a lake trial yields an output detection curve, in which the direct blast is mapped to the background while the acoustic field aberration is represented by the peak value fluctuation. The inhibitory effect in single hydrophone is approximately -5~dB, and is then enhanced by exploiting the mean value removal approach as a preprocessing technique. The direct blast is further suppressed to a level of -10~dB by making full use of multichannel receptions. The main factors affecting the algorithm performance are as follows: the fluctuation degree of the receptions during the weighting vector training period and the power ratio of the forward scattered wave to the direct blast when the target is present.