Jiang Jiajia

A Universal Two-Dimensional Direction of Arrival Estimation Method Without Parameter Match

In this paper, based on the subspace method, a novel algorithm, which does not require match procedure, is proposed to estimate 2-D direction of arrival (DOA) with the L-shaped array. The novel train of thought for DOA estimation includes the following two steps: using the 1-D uniform linear subarray (ULSA) along the z axes, obtain the elevation angle estimates based on the polynomial root method and with the elevation angle estimates and using the 2-D ULSA along the x axes, achieve the estimation of the azimuth angles based on the subspace method. Finally, the proposed algorithm is extended to adapt to the more general array structure. The proposed algorithm obtains much higher detection probability of successful pair matching than the existing algorithms. Simulation results illustrate the validity of the proposed algorithm.

An Efficient Classification Method of Mixed Sources

A simple but effective classification and localization method is presented to distinguish the near- and far-field sources from mixed sources, and estimate the range parameters of near-field sources. To distinguish the near- and far-field sources, He et al. fall back on the oblique projection technique (OPT), which would yield extra estimation errors. In this paper, we do not resort to any other estimation technique (such as OPT), but make good use of known information, so as to achieve the separation of both near-field sources and far-field sources as well as estimation of range of near-field sources. Therefore, the proposed method obtains higher estimation accuracy than the method of He et al. Simulation and comparison results with the method of He et al. show the performance of the proposed method in this paper.

An Effective Frequency-Spatial Filter Method to Restrain the Interferences for Active Sensors Gain and Phase Errors Calibration

In the conventional active calibration algorithms for sensors gain and phase errors, the interference did not be considered. However, the interferences are unavoidable in the practical application. In this paper, an effective frequency-spatial filter (SF) method to restrain the interferences for active sensors gain and phase errors calibration is presented. The proposed method first search the frequency range of the lowest power from the interferences, and then filter out the interferences out of the frequency range through a group of bandpass filter (BF) groups. Further, the proposed method uses an SF to suppress the interferences with nonzero power in the frequency range of the selected BF. Through the above two steps, almost all of interferences can be filtered out. Simulation results illustrate the validity of the proposed method.

A Novel Offshore Acoustic Sensing Array: Unifying Clock Source to Every Hydro-phones Acquisition Node

A high-precision clock source (±2.0 ppm) in the head of array was used to generate unified acquisition and transmission clock, each hydro-acoustic acquisition node recovered local standard clock from the unified source via PLLs. The real-time transmission path of clock and data was pipelined, which is based on RS-485 and positive emitter coupled logic (PECL). Synchronous serial data communicated at 196.608 Mbps by non-shielded twisted-pair (Cat 6) in the length of 100 meters, which can guarantee a strong anti-jamming capability and good real-time features. Clock transmission and data acquisition experiments were carried out in the laboratory, and results show that the hydrophones array can be a good system for real-time undersea acoustic exploration.