Longxiang Guo

Sea trial research on multi-source underwater acoustic image measurement technology based on the sparse array

The underwater acoustic image measurement technology is a technology of passive acoustic localization in near field, which can get the track of moving target by measuring the main noise sources of the target through large scale array. Because of the complexity of underwater environment, it is difficult to lay a large high-accuracy half-wavelength array. Thus it is more convenient to use a sparse array in underwater acoustic image measuring. The sea trial research on the underwater acoustic image measurement based on the sparse array has been done to verify the feasibility of the method. The experiment result shows that using sparse array would lead to a series of interference fringes appearing in the image, but the interference fringes can be removed by frequency-division integrated technology. Three tracks measurement results of a catamaran are given. The results prove that the method is feasible.

Research on selective passive focusing technology based on dummy iterative time-reversal mirror

Multi-passive targets detecting in multi-path and environmental noise conditions is one of the main functions for sonar signal processing. Passive selective focusing and localization methods based on acoustic vector sensors arrays iterative TRM technique is studied and dummy iterative time-reversal mirror (DITRM) is presented in this paper. The output of acoustic vector sensors array DITRM can not only refocuses the incident acoustic field back to the origin of a probe signal regardless of the complexity of the medium, but selective focuses on the less Transmission Lose target. The validity of this method was verified in the simulation experiments. The results show that this technology has higher performance and precision because of TRM vector array processing, and is more robust than pressure only DITRM.

Multitarget Tracking Algorithm Using Multiple GMPHD Filter Data Fusion for Sonar Networks

Multitarget tracking algorithms based on sonar usually run into detection uncertainty, complex channel and more clutters, which cause lower detection probability, single sonar sensors failing to measure when the target is in an acoustic shadow zone, and computational bottlenecks. This paper proposes a novel tracking algorithm based on multisensor data fusion to solve the above problems. Firstly, under more clutters and lower detection probability condition, a Gaussian Mixture Probability Hypothesis Density (GMPHD) filter with computational advantages was used to get local estimations. Secondly, this paper provided a maximum-detection capability multitarget track fusion algorithm to deal with the problems caused by low detection probability and the target being in acoustic shadow zones. Lastly, a novel feedback algorithm was proposed to improve the GMPHD filter tracking performance, which fed the global estimations as a random finite set (RFS). In the end, the statistical characteristics of OSPA were used as evaluation criteria in Monte Carlo simulations, which showed this algorithm’s performance against those sonar tracking problems. When the detection probability is 0.7, compared with the GMPHD filter, the OSPA mean of two sensor and three sensor fusion was decrease almost by 40% and 55%, respectively. Moreover, this algorithm successfully tracks targets in acoustic shadow zones.

A weak target detecting method based on multistatic information fusion

The detecting performance of active sonar have been affected by the weak targets scattering and serious noise background. If artificial reducing the threshold to get high detecting capability, the false alarm probability will be very high. Therefore, this paper propose a weak target detecting method based on multistatic information fusion. After getting more information about the target from different positions and extracting the target feature vectors to make a fusion, a better recogniting performance will be present. The target scattering centers are extracted by CLEAN technique, which could avoid extracting the false scattering centers, and adapt in low signal to noise ratio (SNR). The neural network classifier is used to make a fusion and recognize the target. Simulation results show that this method has better target identification performance and low false alarm probability, demonstrating the target features fusion has high value for active sonar detecting in the future.

The research on the optimal bionic waveform design

In this paper, the authors address the design of optimal waveform for target detection and parameter estimation based on the features analysis of the whistle of Indo-pacific humpback dolphins. A set of types of waveforms exist in the sequence of whistle calls. Considering the perfect performance of non-linear frequency modulated and multi-harmonics structure in anti-range sidelobe and anti-reverberation, several fusion schemes of several kinds of waveforms are explored and fusion results are studied analytically and from simulation. It is concluded that the bionic harmonic fused signal shows good time resolution, and improve the performance of suppressing reverberation. Research result provides nice reference and application value in underwater sonar based on bionic acoustic signal.

Spatial-division-multiplexing (SDM) in time-variant channel based on vector adaptive time-reversal technique

In the field of multistatic remote detection for underwater target, as a time-variant and multi-path channel interfered by environmental noise, underwater acoustic environment limits the spatial share of channel and poses a great challenge against spatial-division-multiplexing(SDM) in multistatic detection. In this paper, a kind of method of spatial-division-multiplexing(SDM) in time-variant channel based on vector adaptive time-reversal technique is proposed. By using time-reversal technique, multi-path structure of channel is efficiently restrained ; Applied adaptive filtering, time-variant characteristic of channel is effectively suppressed; With single vector hydrophone, spatial focus of target echoes and noise interference suppression is accomplished by spatial filtering. Finally, excellent results are performed in spatial-division-multiplexing(SDM) of multistatic detection, supported by the experimental simulation.

Spatial-division-multiplexing in time-variant and multi-path channel based on vector adaptive time reversal technique

In the field of multistatic remote detection for underwater target, as a time-variant and multi-path channel interfered by environmental noise, complex underwater acoustic environment limits the spatial share of channel and poses a great challenge against spatial-division-multiplexing (SDM) in multistatic detection. In this paper, a kind of method of spatial-division-multiplexing(SDM) based on vector adaptive time-reversal technique is proposed. By use of time-reversal technique, multi-path structure of channel is efficiently restrained; Meanwhile, with adaptive filtering applied, time-variant characteristic of channel is effectively suppressed. Moreover, with single vector hydrophone, spatial focus of target echoes and noise interference suppression is accomplished by spatial filtering. Finally, excellent results are performed in SDM of multistatic detection, supported by the experimental simulation.In the field of multistatic remote detection for underwater target, as a time-variant and multi-path channel interfered by environmental noise, complex underwater acoustic environment limits the spatial share of channel and poses a great challenge against spatial-division-multiplexing (SDM) in multistatic detection. In this paper, a kind of method of spatial-division-multiplexing(SDM) based on vector adaptive time-reversal technique is proposed. By use of time-reversal technique, multi-path structure of channel is efficiently restrained; Meanwhile, with adaptive filtering applied, time-variant characteristic of channel is effectively suppressed. Moreover, with single vector hydrophone, spatial focus of target echoes and noise interference suppression is accomplished by spatial filtering. Finally, excellent results are performed in SDM of multistatic detection, supported by the experimental simulation.

Target tracking technology for reducing false alarm

Because of the complex marine environment, there are a large number of false arms when the active sonar is detecting targets. It is difficult to find the real targets, so the false negative rate has a significant increase. In order to suppress the clutter better and reduce the false alarm rate maximally, the problem of target detection via Multiple Hypothesis Tracking based Track Before Detect (MHT -TBD) is considered in this paper. MHT -TBD is a data association method that could remove wild spots in a clutter environment and save useful data. But for high maneuvering targets, the tracking success rate of MHT-TBD is significantly reduced. An improved MHT-TBD method named interactive multimode MHT-TBD (IMM-MHT-TBD), which combines interactive multimode with multi hypothesis tracking is introduced in this paper. It shows a superior performance in high maneuvering targets tracking by maintenance and data association in a clutter environment. Simulation results show that IMM-MHT-TBD can solve the problem of ...

The acoustical features analysis of Indo-Pacific humpback dolphins’ whistle and modeling research

Depending on species-specific characteristics of echolocation and recognition,dolphin could travel in groups without collision, and they could also prey and defend mutually. As a multi-harmonics, frequency-modulated signal, the variety of whistles revealed the rich group identification and location information of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis). This paper introduces the features of whistle on the basis of Joint time-frequency distribution, dealing with recording data collected in the area of Guangxi and Zhanjiang seacoast, in China. Then the ability of individual identification is discussed from the correlation of whistles, we will get the knowledge of dolphins how to cognize the communication information in the complex environment. The transmission loss function will be depicted using the BELLHOP at last. By extracting the acoustical features, the modeling of whistle signal is implemented based on the Sinusoids Model (Buck, 2000). Specifically, the validity of mathematical ...

Multichannel equalization method based on vector time-reversal and decision feedback equalizer technology

A kind of underwater communication receiver combined with Vector Time-Reversal algorithm and multichannel decision feedback equalizer (VTR-MDFE) is studied, which can address the problem of inter-symbol interference and waveform distortion, resulting from time-varying multipath channel. Impacts of environmental noise can be suppressed by use of vector sensor’s combined directivity and Corresponding vector signal processing technology. Meanwhile, error rate is reduced while system capacity is enhanced by time-reversal algorithm’s anti-multipath ability. The performance of VTR-MDFE are proved by simulated results in the communication channel provided by a ray-based acoustic model, for different ocean conditions and source-receiver geometries.