针对信噪比较低时,多重信号分类（Multiple Signal Classification,MUSIC）算法方位谱背景级较高的问题,提出了一种解卷积的MUSIC方位估计算法（Deconvolvecd MUSIC,D-MUSIC）。该方法用一个类似冲激函数作为MUSIC算法输出方位谱的点散...针对信噪比较低时,多重信号分类（Multiple Signal Classification,MUSIC）算法方位谱背景级较高的问题,提出了一种解卷积的MUSIC方位估计算法（Deconvolvecd MUSIC,D-MUSIC）。该方法用一个类似冲激函数作为MUSIC算法输出方位谱的点散射函数（Point Scattering Function,PSF）,然后基于解卷积图像复原理论,利用该点散射函数和RichardsonLucy（R-L）迭代算法对MUSIC算法的方位谱进行解卷积,获得D-MUSIC算法的方位谱,达到降低方位谱背景级的目的。仿真表明,该方法继承了MUSIC算法的高分辨性能,且可以明显降低方位谱的背景级,具有较好的方位估计性能。对南海海上试验的水平阵数据进行处理,分析比较了利用MUSIC算法和解卷积MUSIC算法获得的方位谱时间历程图,分析结果有效验证了D-MUSIC算法性能的优越性。展开更多
To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the arra...To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the array physical size simultaneously, this paper proposes a new underwater 3-D acoustic imaging approach based on a novel multiple-input multiple-output (MIMO) array. Specifically, the MIMO array is composed of four uniform linear arrays (ULAs) located on four sides of a rectangle. The transmitting array composed of two ULAs is located on a pair of opposite sides, and the receiving array composed of another two ULAs is located on the other two sides. Furthermore, narrowband waveforms coded with orthogonal polyphase sequences are employed as transmitting waveforms. When the subcode numbers in the polyphase coded sequences are sufficient, the MIMO array has the same 3-D imaging ability as a rectangular array, which has a two-time bigger size than that of the former. Consequently, the MIMO array can not only save a great number of sensors, but halve the array size, when compared to a rectangular array with the same cross-range resolution. Computer simulations are provided to demonstrate the effectiveness of the proposed imaging approach.展开更多
In deep ocean environments,the bottom bounce mode associated with the low-frequency active sonar is often used to detect the underwater target located in the first shadow zone.However,range estimation error occurs due...In deep ocean environments,the bottom bounce mode associated with the low-frequency active sonar is often used to detect the underwater target located in the first shadow zone.However,range estimation error occurs due to the varying sound speed,which produces a bending acoustic ray path from the sonar to the target.To reduce the active ranging error,a method that uses the effective sound speed can be used.However,this method faces a heavy computation burden due to the calculation of the time delay-effective sound speed pairs at each grid position in the bottom bounce area.To reduce this computation burden,an improved effective sound speed estimation method based on the interference structure of the sound field is proposed.The sound field fluctuation in the bottom bounce area is due to the energy fluctuation of the sound rays having different grazing angles.A quantitative relationship between the detectable areas and the sound rays with high energies is established based on sound ray interference theory.The time delay-effective sound speed pairs in the boundary location of the detectable areas are calculated according to this relationship.Hence,the time delay-effective sound speed pairs at all the grid positions can be obtained by linear fitting.Simulation results show that the improved method can obtain a similar range estimation error as the conventional effective sound speed estimation method but has a much lower computation burden,which is useful for real-time applications.展开更多
基金supported in part by the Doctorate Foundation of Northwestern Polytechnical University(Grant No. CX201101)
文摘To obtain high cross-range resolution, the underwater 3-D acoustic imaging system usually requires a rectangular array with a great number of sensors and a large physical size. To reduce the sensor number and the array physical size simultaneously, this paper proposes a new underwater 3-D acoustic imaging approach based on a novel multiple-input multiple-output (MIMO) array. Specifically, the MIMO array is composed of four uniform linear arrays (ULAs) located on four sides of a rectangle. The transmitting array composed of two ULAs is located on a pair of opposite sides, and the receiving array composed of another two ULAs is located on the other two sides. Furthermore, narrowband waveforms coded with orthogonal polyphase sequences are employed as transmitting waveforms. When the subcode numbers in the polyphase coded sequences are sufficient, the MIMO array has the same 3-D imaging ability as a rectangular array, which has a two-time bigger size than that of the former. Consequently, the MIMO array can not only save a great number of sensors, but halve the array size, when compared to a rectangular array with the same cross-range resolution. Computer simulations are provided to demonstrate the effectiveness of the proposed imaging approach.
基金supported by the National Natural Science Foundation of China(11874061)。
文摘In deep ocean environments,the bottom bounce mode associated with the low-frequency active sonar is often used to detect the underwater target located in the first shadow zone.However,range estimation error occurs due to the varying sound speed,which produces a bending acoustic ray path from the sonar to the target.To reduce the active ranging error,a method that uses the effective sound speed can be used.However,this method faces a heavy computation burden due to the calculation of the time delay-effective sound speed pairs at each grid position in the bottom bounce area.To reduce this computation burden,an improved effective sound speed estimation method based on the interference structure of the sound field is proposed.The sound field fluctuation in the bottom bounce area is due to the energy fluctuation of the sound rays having different grazing angles.A quantitative relationship between the detectable areas and the sound rays with high energies is established based on sound ray interference theory.The time delay-effective sound speed pairs in the boundary location of the detectable areas are calculated according to this relationship.Hence,the time delay-effective sound speed pairs at all the grid positions can be obtained by linear fitting.Simulation results show that the improved method can obtain a similar range estimation error as the conventional effective sound speed estimation method but has a much lower computation burden,which is useful for real-time applications.
