提出了一种迭代算法，在FIR数字滤波器的自适应设计过程中自动改变各个频率指标上代价因子的值，最终实现代价因子的最优取值。利用这种改进方法，可以实现FIR数字滤波器和设计指标之间的最佳拟合。给出了两个设计实例，其中幅度响应每倍频程衰减6dB的滤波器，可以用于模拟水声阵列接收的宽带海洋噪声，而高精度时延的滤波器，则可以实现波束形成中所需要的非整数倍采样间隔的时延。

The problem of beamforming and related beamspace high resolution direction-of-arrival (DOA) estimation is studied in this paper. All beamspace processing methods are based on the beam outputs and the beampattern design plays an important role in providing high quality beam output data for further processing. Three typical situations which are frequently encountered in practical sonar system working environment and the most widely studied MUSIC algorithm are considered herein. First, when isotropic noise is the dominant noise at sensors, conventional beamforming techniques provide the optimum performance in the sense that DOA estimate is the ML estimate. Good DOA estimates are obtainable by applying MUSIC to the beam outputs directly. Then, uncorrelated interferes with much higher strength than the wanted signals are assumed to be present in the sidelobe region, and low sidelobe Dolph-Chebyshev and adaptive MVDR beampatterns are designed to guarantee the performance of MUSIC. And finally, the robustness of conventional techniques is combined with the adaptivity of MVDR beamforming to deal with the situation when the interfere in the sidelobe region is strongly correlated with one of the wanted sources. Performance in all three situations is studied with numerical examples.

针对空气中基于时延的任意阵列被动定向问题，提出了一种基于最小二乘法的统一模型，并对影响该模型定向精度的几种因素进行了深入的分析。由于可以用于任意结构阵形，该统一模型能够方便地分析阵元位置误差引起的定向误差，能够避免实际系统由于更换阵形而带来的较大的软件变化；并且，当实际阵列与设计模型存在较大误差时，可以方便地改变模型参数使其与实际的阵列匹配。对影响定向误差的各种因素的分析和计算机仿真，为确定和提高被动声定向的精度提供了有价值的参考。

The generalized steering vector is blindly estimated from the CM array, where the steering vectors to all coherent signals are reconstructed directly by using the property of sub-array shift-invariance. When used as the array weighting, the steering vectors will provide recovered signals in corresponding beams. DOAs can be estimated from the angular spectrum subsequently. esults from the computer simulations and the real data analysis.are in good agreement with theoretical analysis. Our method not only can resolve closely spaced coherent signals, but also is shown to be more robust to system errors compared to some other DOA estimation algodthms.

In this paper, a new method is presented to design low-sidelobe wideband constant beamwidth beamformers (WCBB) in time domain, which alleviates the effect caused by array mismatch errors by applying the measured array models into the design procedure. A combination of FIR filters and digital delay lines is used in the beamformer structure to reduce the order of FIR filters. In FIR filter design, the semi-definite programming is utilized which is able to constrain both the mainlobe shapes and the sidelobe levels within the whole design frequency band. Results from lake experiments with a practical sonar system verified the effectiveness of the proposed method.