基于快速傅里叶变换直流分量的土壤电阻率测量

Measurement of soil resistivity based on FFT DC component

提出一种新的土壤电阻率测量方法—快速傅里叶变换(FFT)直流分量法,研究了该方法所涉及的激励信号类型、测量信号的采集及处理、测量的精确度和稳定性验证等。首先分别分析了传统土壤电阻率测量方法采用直流供电和交流供电的益处和弊端,在此基础上,提出采用直流和交流组合波作为土壤的激励信号来克服传统测量方法的不足。然后,讨论了如何采用FFT直流分量法在频域上分离出测量信号中的直流分量。最后,设计了土壤电阻率测量系统。通过土壤导电模型电路实验确定了激励信号的直流分量、频率等参数的大小,并验证了系统的测量准确度。与传统测量方法做了对比实验,进一步验证了测量结果的稳定性。实验结果显示,模型电路电阻率的测量误差在1%以内,实际土壤电阻率测量数据的方差为0.42,表明用提出的方法测量土壤电阻率,测量结果准确性好,稳定性高。

A new measurement method for soil resistivity, Fast Fourier Transform（FFT） DC compo- nent method, was put forward, and corresponding power signal supply, acquisition and processing of measurement signals, measuring accuracy and data stability in the measurement were explored. First, the benefits and drawbacks of the traditional measurement methods for soil resistivity using the DC or AC power supplies were analyzed, respectively. Based on above analy and AC was adopted as the excitation signal of the soil to overcome th sis, a combination signal of DC e deficiency of traditional meas urement methods. The domain was discussed. the DC component and how to isolate the DC component of the measurement signal in a frequency nally, a measurement system for soil resistivity was established. The size of e frequency of the excitation signal were determined by a circuit experiment on the soil conductivity model, and the measurement accuracy of the system was verified. Further- more, the stability of the measurement results was confirmed by comparing with those of traditional methods. Experimental results indicate that the error of resistivity measurement in model circuit is less than 1%, and the variance of the actual soil resistivity measurement data is 0.42, which proves that soil resistivity measurement results are reliable, accurate and stable by proposed method.