用调制解调技术降低地震数据采集器的漂移

地震数据采集是数字化地震观测的重要环节, 因为模拟数字转换器(A/D)是地震数据采集器的重要部件, A/D的技术水准在很大程度上决定了数据观测质量。 放大器及A/D的漂移和 1/f噪声是数据采集器漂移的主要来源, 对以低频信号观测为主要特征的地震观测有较大影响。 为降低其影响, 本文在算法上对此问题做了一些探讨, 在目前autozero技术上做出一些改进, 即用调制解调技术来降低1/f噪声对信号精度的影响, 并做了相应的算法模拟。 在此基础上, 对算法做了进一步改进, 利用高次谐波加权求和使输出信噪比得到一定程度的提高。 结果表明, 通过优化解调算法, 可以进一步提高信噪比约2 dB, 对试验电路获得的测试数据应用优化解调算法也证实了这一点。

Reducing Drifting in Seismic Data Acquisition Using Modulation-demodulation Technique

Digital seismic data acquisition is an important part in earthquake observation, and analog-digital converter technology standards largely determine the quality of the data observation, and data acquisition will produce 1/f noise characteristic to the observation accuracy in the low frequency range. This paper discussed this issue based on an algorithm theory for improving the quality of seismic signals. We proposed an improved algorithm based on the autozero technology and modulation technology for weakening 1/f noise and imitated in the process. We also analyzed the energy loss of square wave and sine wave modulation and demodulation sequence as a weighted average for proposing the algorithm and proved the correctness of the weighted average algorithm in theory. Experimental data also show that the signal to noise ratio has been improved to some extent, and are well consistent with the calculated values.