子阵和相位平滑的相位差方向估计方法

Estimation of Arrival Direction for Phase Difference Method Using Sub Array and Phase Unwrapping

针对相位差波达方向(DOA)估计方法(PDM)的均方根误差偏离克拉-美罗界较多的问题,提出了子阵和相位平滑的相位差方向估计方法(SUPDM).首先将阵列接收信号转换到频域,并把阵列划分为若干子阵,然后对各子阵中心频点处的频谱作相干平均后得到各子阵的输出频谱,再求取输出频谱的相位并进行纵向相位平滑,以平滑后相位的最大最小值的差值的倒数作为方向估计算子,最后采用角度搜索得到方向估计算子的峰值所对应的角度,即为SUPDM的方向估计结果.在不同信噪比和不同角度间隔下,SUPDM的方向估计性能均优于PDM,当存在频谱泄漏时,SUPDM的成功分辨率仍高于PDM和常规波束形成算法.仿真结果表明,在单源入射、信噪比为-5dB时,SUPDM比PDM的均方根误差小0.03°.

The phase difference method using sub array and phase unwrapping（SUPDM）is presented to improve the arrival direction estimation of the phase difference method（PDM）.The sensor outputs are transformed into the frequency domain,and the array is divided into several sub arrays.The coherent average is calculated on the spectra at the center frequency bin in each sub array,and phase angles of the resulting spectra are obtained.Then the transverse phase unwrapping is applied to these phase angles.The reciprocal of the phase difference between the maximum phase and the minimum phase is taken as the DOA estimator,and the peak locations of the spatial spectrum give the DOA estimation.The SUPDM has better performance than that of the PDM under different signal to noise ratios and source separations.The resolution capability of the SUPDM is superior to that of both the PDM and the conventional beam-former when there exists spectrum leakage.The simulation results show that,the root mean square error of the SUPDM estimation has 0.03degree smaller than that of the PDM when there is single source and the signal to noise ratio is-5dB.