Abstract: The present invention provides a method of source number estimation based on eigenspace in DOA estimation, including: (1) obtaining signals received by uniform linear array; (2) calculating a covariance matrix according to the received signals; (3) calculating a complex-valued covariance matrix or a covariance matrix after real-valued computations; (4) conducting eigendecomposition to the covariance matrix to obtain its eigenvector matrix; (5) calculating a source number decision based on the eigenvector; (6) calculating a ratio; and (7) source number estimation. The present invention can accurately estimate source number and save huge amounts of computation during signal processing in DOA estimation, and lower the cost of hardware.

Abstract: The present invention discloses a method and a system for measuring flow layer velocities using correlation velocity measuring sonar. The present invention provides a new theoretical expression for fluid medium sonar array temporal and spatial correlation function, the velocities of each flow layer are derived by fitting experimental data and a theoretical function, or fitting absolute value operated and localized experimental data and a theoretical function. The fluid medium sonar array temporal and spatial correlation function of the present invention is succinctly expressed by Kummer function, and well coincided with the experiments. This function is applicable not only to far field region, i.e. planar wave region, but also Fraunhofer region, i.e. spherical wave region. The present invention has the merits of high measurement accuracy, small calculation load, good robustness and fast convergence.

Abstract: The present invention provides a method of source number estimation based on eigenspace in DOA estimation, including: (1) obtaining signals received by uniform linear array; (2) calculating a covariance matrix according to the received signals; (3) calculating a complex-valued covariance matrix or a covariance matrix after real-valued computations; (4) conducting eigendecomposition to the covariance matrix to obtain its eigenvector matrix; (5) calculating a source number decision based on the eigenvector; (6) calculating a ratio; and (7) source number estimation. The present invention can accurately estimate source number and save huge amounts of computation during signal processing in DOA estimation, and lower the cost of hardware.

Abstract: A processing method of this invention relates to an angle of arrival estimation technique, where by a high resolution bathymetric sidescan sonar signal process method it measure the micro-geomorphy of the sea bottom. That is the multi-subarray sub-space fitting method. The invention shows that when the array elements number is fixed, no matter there is mutual coupling or not between array elements, there exists one subarray which has the smallest phase estimation standard deviation, the method of this invention overcomes the phase error caused by mutual coupling and enhances the measurement precision.

Abstract: The present invention discloses a method and a system for measuring flow layer velocities using correlation velocity measuring sonar. The present invention provides a new theoretical expression for fluid medium sonar array temporal and spatial correlation function, the velocities of each flow layer are derived by fitting experimental data and a theoretical function, or fitting absolute value operated and localized experimental data and a theoretical function. The fluid medium sonar array temporal and spatial correlation function of the present invention is succinctly expressed by Kummer function, and well coincided with the experiments. This function is applicable not only to far field region, i.e. planar wave region, but also Fraunhofer region, i.e. spherical wave region. The present invention has the merits of high measurement accuracy, small calculation load, good robustness and fast convergence.

Abstract: A processing method of this invention relates to an angle of arrival estimation technique, where by a high resolution bathymetric sidescan sonar signal process method it measure the micro-geomorphy of the sea bottom. This is the multi-subarray sub-space fitting method. The invention shows that when the array elements number is fixed, no matter there is mutual coupling or not between array elements, there exists one sub-array which has the smallest phase estimation standard deviation, the method of this invention overcomes the phase error caused by mutual coupling and enhances the measurement precision.

Abstract: A method and a system for measuring the velocity of a vessel relative to the bottom using a velocity measuring correlation sonar are disclosed. The present invention provides a new theoretical expression for the bottom medium sonar array temporal and spatial correlation function. The velocity of the vessel relative to the bottom is derived by fitting experimental data to a theoretical function. The bottom medium sonar array temporal and spatial correlation function of the present invention is succinctly expressed in zero-rank Bessel function, and well coincided with experiments. The function is applicable not only to far field region, i.e. planar wave region, but also to Fraunhofer region, i.e. spherical wave region. Transmit transducers and receive transducers are multistatic in the velocity measuring correlation sonar of the present invention, so the transmit beam width and the receive beam width can be selected reasonably.

Abstract: A method and a system for measuring the velocity of a vessel relative to the bottom using a velocity measuring correlation sonar are disclosed. The present invention provides a new theoretical expression for the bottom medium sonar array temporal and spatial correlation function. The velocity of the vessel relative to the bottom is derived by fitting experimental data to a theoretical function. The bottom medium sonar array temporal and spatial correlation function of the present invention is succinctly expressed in zero-rank Bessel function, and well coincided with experiments. The function is applicable not only to far field region, i.e. planar wave region, but also to Fraunhofer region, i.e. spherical wave region. Transmit transducers and receive transducers are multistatic in the velocity measuring correlation sonar of the present invention, so the transmit beam width and the receive beam width can be selected reasonably.

Abstract: The present invention relates to a method and a system of a high code speed low error probability underwater acoustic coherent communication for underwater transferring instruction, data and image. The communication system includes a host machine installed on a mother ship or a main control underwater vehicles A and a guest machine installed on an underwater vehicle B, wherein the host machine comprises an electronic subassembly, a transducer and a receiving line array which is vertically deployed and consists of more than two hydrophones, and the guest machine comprises an electronic subassembly and a transmitting/receiving transducer.

Abstract: A high resolution bathymetric sidescan sonar system for measuring micro-geomorphy of the sea bottom having an underwater vehicle, an underwater electronic subsystem mounted on the underwater vehicle and containing a transmitter and a receiver, and two sonar arrays mounted symmetrically on two sides of a lower part of the underwater vehicle and being connected to the underwater electronic subsystem through a cable. Each sonar array has a transmitting linear array and three or more parallel receiving linear arrays. The parallel receiving linear arrays are arranged at equal spaces, and the space d between two adjacent parallel receiving linear arrays is ?>d??/2, in which ? is a wavelength of an acoustic wave, and an operation frequency of the parallel receiving linear arrays ranges from 30 kHz to 1200 kHz.

Abstract: A high resolution bathymetric sidescan sonar system for measuring micro-geomorphy of the sea bottom having an underwater vehicle, an underwater electronic subsystem mounted on the underwater vehicle and containing a transmitter and a receiver, and two sonar arrays mounted symmetrically on two sides of a lower part of the underwater vehicle and being connected to the underwater electronic subsystem through a cable. Each sonar array has a transmitting linear array and three or more parallel receiving linear arrays. The parallel receiving linear arrays are arranged at equal spaces, and the space d between two adjacent parallel receiving linear arrays is ?>d??/2, in which ? is a wavelength of an acoustic wave, and an operation frequency of the parallel receiving linear arrays ranges from 30 kHz to 1200 kHz.