Two optimal beamforming approaches for sensor arrays with arbitrary shapes and element directivities are proposed. The first one minimizes the sidelobe level while keeping the distortionless response in the direction ...Two optimal beamforming approaches for sensor arrays with arbitrary shapes and element directivities are proposed. The first one minimizes the sidelobe level while keeping the distortionless response in the direction of the desired signal and maintaining the mainlobe width. The second approach maximizes the array gain while keeping the mainlobe direction and controling the sidelobe level which is strictly guaranteed to be below a prescribed value. Array weight norm constraint is used to improve the robustness of the two optimal beamforming approaches against random errors. The first approach provides the optimal tradeoff among the sidelobe level, the beamwidth and robustness; and the second approach provides the optimal tradeoff among the array gain, the sidelobe level and robustness. Both optimal beamforming problems are formulated as the second-order cone programming which can be easily solved using well-developed interior-point methods. Results of computer simulations and lake-experiment for a circular array demonstrate superior performance of the approaches proposed in this paper in comparison to some existing adaptive-based algorithms.展开更多
An approach to designing time domain broadband frequency invariant beamformer via optimal array pattern synthesis and optimal FIR filters design is proposed. First, the working frequency band is decomposed into a numb...An approach to designing time domain broadband frequency invariant beamformer via optimal array pattern synthesis and optimal FIR filters design is proposed. First, the working frequency band is decomposed into a number of narrow band frequency bins.The array weights at each frequency bin are designed via optimal array pattern synthesis methods to insure that the synthesized pattern approximates the desired one within the mainlobe area. Then, a bank of FIR filters corresponding to the input channels are designed to provide the frequency responses that approximate the array weights in the working frequency band for each sensor. Finally, each sensor feeds a FIR filter and the filter outputs are summed to produce the beam output time series. Both array pattern synthesis and FIR filters design problems are formulated as the second-order cone programming (SOCP), which can be easily solved using well-developed interior-point methods. Results of computer simulations and lake-experiment for a twelve-element semicircular array demonstrate satisfactory performance of the proposed approach.展开更多
An approach to improving the performance of matched field localization by introducing a generalized spa-tial filter to suppress interference noise and pass the signal of interest with minimal distortion is presented. ...An approach to improving the performance of matched field localization by introducing a generalized spa-tial filter to suppress interference noise and pass the signal of interest with minimal distortion is presented. The spatial filter is designed by minimizing the maximum distortion of the filtered replica vectors within passband while guaran- teeing the norm of the filter response within the stopband to be lower than some given threshold values. We show that the design problem can be formulated as the second-order cone programming (SOCP) which can be solved efficiently via the well-established interior point method. A modified matched field processor is given to ultimately eliminate the effect of the distortion in the spatially filtered replica vectors. Computer simulation results confirm the effectiveness of the proposed approach by localizing a weak source in the pres-ence of a strong interferer and noise.展开更多
Discrete noise source suppression in underwater acoustic channel has attracted great attention in recent years. The paper proposes a new principle for dealing with the problem. This new principle is called matched fie...Discrete noise source suppression in underwater acoustic channel has attracted great attention in recent years. The paper proposes a new principle for dealing with the problem. This new principle is called matched field noise suppression (MFNS). Based on a previous work of the authors group, a full understanding about how a discrete noise source shows effects on the performance of a towed hydrophone line array has been obtained. In light of that finding, MFNS is proposed, which explores and utilizes the characteristics of the noise transmission channel to achieve much greater suppression of the noise in comparison with existing approaches. MFNS combines the concept of matched field processing (MFP) and optimal sensor array processing (OSAP) together to suppress the discrete noise source and to maintain an optimal beam for receiving far-field wanted plane wave signals. A MFNS beam-former is deduced in constraint with signal plane-wave response being unit and noise matched field response being zero. A closed-form solution of the weight vector for the beam-former is given. Computer simulation results agree well to the theoretical analysis.展开更多
The performance of the multistage Constant Modulus (CM) array, one of the most striking blind beamforming algorithms, for the source Directions-of-Arrival (DOA) estimation was analyzed via computer simulations and wat...The performance of the multistage Constant Modulus (CM) array, one of the most striking blind beamforming algorithms, for the source Directions-of-Arrival (DOA) estimation was analyzed via computer simulations and water tank experiments, and was compared to that of other DOA estimation algorithms including the 'non-blind' and the 'blind'. Firstly, a nominal array model and an array model with gain and phase perturbations were established, respectively. Secondly, the multistage CM array algorithm was described and computer simulations were conducted. Simulation results showed that the multistage CM array could correctly estimate the DOA at the same time when the sources were blindly recovered, and the angle separating ability of the algorithm was beyond the Rayleigh resolution limit. By changing the variance of the array model errors, it was also verified that the multistage CM array was more robust to the errors than some other algorithms mentioned in this paper. Finally, water tank experiments and data processing results were provided. Situations with different array sizes and source angular separations were considered. It was shown that the results were in good agreement with computer simulations. Results of computer simulations and water tank experiments verified that the DOAs of the multiple independent sources could be blindly and robustly estimated with the multistage CM array.展开更多
A method of two-dimensional direction of arrival (DOA) estimation for low altitude target, which is based on intensity measurement using a three-dimensional differential pressure acoustic vector-sensor, is presented. ...A method of two-dimensional direction of arrival (DOA) estimation for low altitude target, which is based on intensity measurement using a three-dimensional differential pressure acoustic vector-sensor, is presented. With the perfect characteristics of acoustic vector sensor in the low frequency band, accurate DOA estimation is achieved under small array size. The validity of the proposed method was assessed by experiments on the noise signals radiated by a helicopter. The influence of acoustic sensor size, integral time and signal to noise ratio to the accuracy of DOA estimation were investigated, respectively. The performance comparisons demonstrated that it outperformed the traditional time-delay measurement based method for a small acoustic array.展开更多
文摘Two optimal beamforming approaches for sensor arrays with arbitrary shapes and element directivities are proposed. The first one minimizes the sidelobe level while keeping the distortionless response in the direction of the desired signal and maintaining the mainlobe width. The second approach maximizes the array gain while keeping the mainlobe direction and controling the sidelobe level which is strictly guaranteed to be below a prescribed value. Array weight norm constraint is used to improve the robustness of the two optimal beamforming approaches against random errors. The first approach provides the optimal tradeoff among the sidelobe level, the beamwidth and robustness; and the second approach provides the optimal tradeoff among the array gain, the sidelobe level and robustness. Both optimal beamforming problems are formulated as the second-order cone programming which can be easily solved using well-developed interior-point methods. Results of computer simulations and lake-experiment for a circular array demonstrate superior performance of the approaches proposed in this paper in comparison to some existing adaptive-based algorithms.
基金This work was supported by the National Natural Science Foundation of China (60472073) and (10304015).
文摘An approach to designing time domain broadband frequency invariant beamformer via optimal array pattern synthesis and optimal FIR filters design is proposed. First, the working frequency band is decomposed into a number of narrow band frequency bins.The array weights at each frequency bin are designed via optimal array pattern synthesis methods to insure that the synthesized pattern approximates the desired one within the mainlobe area. Then, a bank of FIR filters corresponding to the input channels are designed to provide the frequency responses that approximate the array weights in the working frequency band for each sensor. Finally, each sensor feeds a FIR filter and the filter outputs are summed to produce the beam output time series. Both array pattern synthesis and FIR filters design problems are formulated as the second-order cone programming (SOCP), which can be easily solved using well-developed interior-point methods. Results of computer simulations and lake-experiment for a twelve-element semicircular array demonstrate satisfactory performance of the proposed approach.
文摘An approach to improving the performance of matched field localization by introducing a generalized spa-tial filter to suppress interference noise and pass the signal of interest with minimal distortion is presented. The spatial filter is designed by minimizing the maximum distortion of the filtered replica vectors within passband while guaran- teeing the norm of the filter response within the stopband to be lower than some given threshold values. We show that the design problem can be formulated as the second-order cone programming (SOCP) which can be solved efficiently via the well-established interior point method. A modified matched field processor is given to ultimately eliminate the effect of the distortion in the spatially filtered replica vectors. Computer simulation results confirm the effectiveness of the proposed approach by localizing a weak source in the pres-ence of a strong interferer and noise.
文摘Discrete noise source suppression in underwater acoustic channel has attracted great attention in recent years. The paper proposes a new principle for dealing with the problem. This new principle is called matched field noise suppression (MFNS). Based on a previous work of the authors group, a full understanding about how a discrete noise source shows effects on the performance of a towed hydrophone line array has been obtained. In light of that finding, MFNS is proposed, which explores and utilizes the characteristics of the noise transmission channel to achieve much greater suppression of the noise in comparison with existing approaches. MFNS combines the concept of matched field processing (MFP) and optimal sensor array processing (OSAP) together to suppress the discrete noise source and to maintain an optimal beam for receiving far-field wanted plane wave signals. A MFNS beam-former is deduced in constraint with signal plane-wave response being unit and noise matched field response being zero. A closed-form solution of the weight vector for the beam-former is given. Computer simulation results agree well to the theoretical analysis.
基金the Doctorate Creation Foundation of Northwestern Polytechnical University (200203).
文摘The performance of the multistage Constant Modulus (CM) array, one of the most striking blind beamforming algorithms, for the source Directions-of-Arrival (DOA) estimation was analyzed via computer simulations and water tank experiments, and was compared to that of other DOA estimation algorithms including the 'non-blind' and the 'blind'. Firstly, a nominal array model and an array model with gain and phase perturbations were established, respectively. Secondly, the multistage CM array algorithm was described and computer simulations were conducted. Simulation results showed that the multistage CM array could correctly estimate the DOA at the same time when the sources were blindly recovered, and the angle separating ability of the algorithm was beyond the Rayleigh resolution limit. By changing the variance of the array model errors, it was also verified that the multistage CM array was more robust to the errors than some other algorithms mentioned in this paper. Finally, water tank experiments and data processing results were provided. Situations with different array sizes and source angular separations were considered. It was shown that the results were in good agreement with computer simulations. Results of computer simulations and water tank experiments verified that the DOAs of the multiple independent sources could be blindly and robustly estimated with the multistage CM array.
基金the National Natural Science Foundation of China(60372086)and the Doctorate Foundation of Northwestern Polytechnical University,China(200204).
文摘A method of two-dimensional direction of arrival (DOA) estimation for low altitude target, which is based on intensity measurement using a three-dimensional differential pressure acoustic vector-sensor, is presented. With the perfect characteristics of acoustic vector sensor in the low frequency band, accurate DOA estimation is achieved under small array size. The validity of the proposed method was assessed by experiments on the noise signals radiated by a helicopter. The influence of acoustic sensor size, integral time and signal to noise ratio to the accuracy of DOA estimation were investigated, respectively. The performance comparisons demonstrated that it outperformed the traditional time-delay measurement based method for a small acoustic array.
