伪随机源时间域航空电磁响应系统辨识

Identification of Time Domain Airborne Electromagnetic Response with Pseudo-Random Binary Sequence

在时间域航空电磁系统中,采用高频伪随机序列作为激励源是实现浅层高分辨地质探测的有效途径。为了提高大地脉冲响应的辨识精度,在基本相关辨识方法的基础上,本文提出了一种基于时间域循环相关计算的高精度辨识方法,通过消除旁瓣效应影响和在时间域下求解维纳-霍夫方程获取大地脉冲响应。数值模拟仿真结果表明,辨识大地响应相对误差均方根为2.2×10^(-7),早期大地响应辨识误差小于10^(-10)。该高精度辨识方法具有较好的噪声压制能力,在观测时间较短时,单周期辨识提升的信噪比为8.7 dB,优于同等条件下线性叠加降噪方法提升的信噪比6.1 dB。

In the time domain airborne electromagnetic system, using high-frequency pseudo-random binary sequence as excitation source is an effective way to realize shallow high-resolution geological exploration. In order to improve the identification accuracy, a high-precision identification method based on time-domain cyclic correlation calculation is proposed in this paper. The impulse response of the Earth is obtained by eliminating the side lobe effect and solving the Wiener-Hoff equation in the time domain. The numerical simulation results show that the root mean square value of the relative error in identifying the Earth response is 2.2 × 10^(-7),while the identification error of the Early earth response is less than 10^(-10), which proves that this identification method is accurate. Further analysis shows that this high-precision identification method has strong noise suppression ability in a short observation time. The signal-to-noise ratio improved by the single-period identification method is 8.7 dB, which is better than the 6.1 dB improved by the linear superposition noise reduction method under the same conditions.