线列组合阵超宽带恒定束宽波束形成器的实现方法

Realization of wideband constant beamwidth beamformer by linear combined array

声纳处理超宽频带信号时,往往需要较多的阵元以保证低频端有足够大的阵列孔径。阵元个数的增多,必然加重系统设计负担和处理负担。针对上述困难,设计了线性组合阵列,将宽带信号按照频率倍数关系分成多个倍频程子带信号,对不同的子带使用相应的子阵进行接收。为避免栅瓣的出现,子阵阵元间距取为子带最高频率对应波长的一半。各子阵中心位于同一点,这样不同子阵可以共用某些阵元,减小了系统处理的通道数。各子阵采用低旁瓣时域恒定束宽波束形成器设计方法。通过改变采样率,各子阵共用设计出的滤波器组,从而降低了处理器算法的运算量,实现了全频段低旁瓣恒定束宽波束形成器的设计。最后,进行了仿真,验证了算法的有效性。

When the sonar deals with wideband signals, many elements are often needed to guarantee enough array aperture at the bottom frequency. With the number of elements increased, more difficul- ties will appear in the design and disposal of the system. In order to solve the above problems, the li- near combined array was designed. The wideband signal was splitted into several octave bandwidth subbands in term of diploid frequency, and each subband was received by the corresponding subarray. To avoid the grating lobe, the space between elements of each subarray was set as half-wavelength of upmost frequency in each subband. The center of each subarray was the same point, so the different subarrays could share some elements which reduced the channels. Each subarray was designed for low-sidelobe constant beamwidth beamformer in time domain. The sampling frequency changes with the subarray, which makes the computational load much lower by using the designed filters thus to realize the design of wideband low-sidelobe constant beamwidth beamformer. Finally, the validity of methods mentioned was verified by simulating on computer.