旋转加速度计式重力梯度仪输出解调与滤波

Gradient signal demodulation and filtering for rotating accelerometer gravity gradiometer

重力梯度仪是对地球表面微小重力梯度变化进行连续测量的仪器。由于核心敏感元件加速度计工艺与性能水平限制,以及多环节安装误差等因素导致系统实际输出信号中包含了大量噪声,且信噪比极低,为了能够在强噪声中有效提取真实的重力梯度信号,需在信号解调过程中降低谐波干扰引起的测量偏差。结合误差产生机理,分析比较了不同的解调方法对重力梯度信号解调的影响,明确了合理的信号解调手段。同时,在数据处理过程中增加带通滤波环节,进一步降低动态噪声对系统的影响。结合动态摇摆实验数据的仿真验证结果表明:上述措施对重力梯度仪原始观测数据的噪声抑制具有明显效果,测量偏差在一定程度上得到解决,解调后信号的噪声幅度下降至20%,提高了系统的空间分辨率,具有工程化应用意义。

In rotating accelerometer gravity gradiometer, due to the limitation of the accelerometer＇s process and performance level and the effects of various installation errors, there are lots of noises in the system output signal, and the SNRs are extremely low.In order to effectively extract the real gravity gradient signals in strong noises, the measurement errors caused by harmonic interference must be reduced in the process of signal demodulation.Combined with the error generation mechanism, the influences of different demodulation methods on the gravity gradient signal demodulation are analyzed and compared, and a reasonable method of signal demodulation is chosen.Meanwhile, a band-pass filter is added in the data processing process to further reduce the influence of the dynamic noise.Combined with dynamic swing test data, the simulations show that the above measures have obvious effect on the noise suppression of the original gravity data, and the noise amplitude of the demodulated signal is reduced to 20%, which improves the spatial resolution of the system, and has the engineering application value.