用于电磁法观测系统开机自检的信号发生器实现方法

摘要

To meet the boot-strap self-test requirements of electromagnetic prospecting systems,the characteristics of self-test signals of commonly used geophysical instruments and measurement systems are analyzed.Through doing comparison and analysis on existing mechanisms,a novel method is proposed with low-power consumption,high precision,as well as easy realization.A set of implementation circuit is designed and simulated.The circuit is shown to have a strong stability on the basis of Bode and Nyquist diagrams.The simulation and test results show that a self-test pulse with a range of 20 μV～2 V amplitude and 1 Hz～100 kHz frequency can be generated through switches.And the signal frequency stabilizes at 1％;phase stability is no more than 1.5 ％ through repeated test,and amplitude error can be optimized to less than 1％.Using the stable harmonic component of the self-test pulse signal,a response in wider band of the measurement system can be obtained.The practical application demonstrates that the boot selftest model has a power consumption less than 0.3 Watt;and an amplitude between 20 μV and 2 V,and frequency range of 1 Hz～100 kHz.This is consistent with the simulation.The selftest model is applied to a monitoring system.The model has the advantages of stable performance,convenient operation,low cost,and easy-to-design.It can improve present self-test models.%针对电磁法观测系统在使用过程中的开机自检要求,分析常用测量系统及地球物理仪器的检测信号特征,通过对已有机制进行研究和对比,结合现有信号产生电路的优势,提出一种功耗低、精度高、设计简单的自检信号发生器实现方案.基于该方案设计了一套实现电路,其以CPLD为核心,由精密参考电压源、模拟开关及运算放大器等器件构成,并对该电路进行仿真与测试.通过系统稳定性分析,采用波特图与奈奎斯特图表明信号发生电路的稳定性符合设计要求.经仿真与测试,能够通过换挡开关产生幅值为20 μV～2 V、频率范围在1 Hz～100 kHz的自检脉冲信号,频率稳定在1％,重复测试相位稳定度小于1.5％,幅值误差可以优化到1％以内,且能通过其稳定的谐波分量来获取该系统带宽更宽的通道测试响应.测试结果表明,该自检信号发生器电路实际功耗小于0.3W,20 μV～2 V幅值范围和1 Hz～100 kHz频率范围内性能指标的测量结果和仿真结果相符,并成功应用于某监控系统.利用该信号发生器电路实现自检具有操作方便、成本低、易于设计等优点,能够有效的弥补其它自检模式的缺陷.