Zongxin Sun

Kite-type passive acoustic detection system for underwater small targets

Potential underwater threats from some small intruders may pose a significant risk to security of some important waterside infrastructures, coastal facilities, subsea pipelines and ships by terrorists or hostile forces. Detection and tracking technologies in farther range are required to counter such threats by taking an appropriate response in time. The limitations of active sonar in high cost, negative effects on marine life, low covertness and high reverberation have stimulated researches in passive detection methods. The Kite-type Passive Acoustic Detection System (KPADS) was developed to provide alarms in the area of underwater security and protection against terrorism intruders and threats from the waterside, including unmanned underwater vehicles, small submarines, surface vessels, divers and underwater robots etc. This paper reports on the detection and tracking of stationary noise source and moving targets in Fuxianhu Lake of China. A series of technologies is applied to a passive triangular array of 18 hydrophones in a uniformly-spaced linear arrangement. Experimental results are presented demonstrating the system performance of detection range up to 8000m, tracking better not less than 4000m, bearing accuracy up to 1°, and are verified by GPS ground truth.

Kalman filter restraining outliers for short baseline system

In short baseline underwater acoustic positioning system, the outliers will be included in measurement data because of noise and multi-path channel environment. In this paper, we introduce a modified Kalman filter that can perform robust based on innovation variance, this method solves the problem of filtering divergence effectively by modifying the supplement matrix. Finally the processing result of the experiment data in lake is given. The experiment result indicates that using the method can be efficiently a smooth processing to the localization result.

Digital Self-Interference Cancellation for Asynchronous In-Band Full-Duplex Underwater Acoustic Communication

To improve the throughput of underwater acoustic (UWA) networking, the In-band full-duplex (IBFD) communication is one of the most vital pieces of research. The major drawback of IBFD-UWA communication is Self-Interference (SI). This paper presents a digital SI cancellation algorithm for asynchronous IBFD-UWA communication system. We focus on two issues: one is asynchronous communication dissimilar to IBFD radio communication, the other is nonlinear distortion caused by power amplifier (PA). First, we discuss asynchronous IBFD-UWA signal model with the nonlinear distortion of PA. Then, we design a scheme for asynchronous IBFD-UWA communication utilizing the non-overlapping region between SI and intended signal to estimate the nonlinear SI channel. To cancel the nonlinear distortion caused by PA, we propose an Over-Parameterization based Recursive Least Squares (RLS) algorithm (OPRLS) to estimate the nonlinear SI channel. Furthermore, we present the OPRLS with a sparse constraint to estimate the SI channel, which reduces the requirement of the length of the non-overlapping region. Finally, we verify our concept through simulation and the pool experiment. Results demonstrate that the proposed digital SI cancellation scheme can cancel SI efficiently.