Abstract: GS-15 gravity meter gains a high accuracy in the light of measuring relative change of gravitation through shifting swing bar; the capicity tranducer is used here in measuring the shift.Conventional gravity meter tends to loss the high-frequency component of 0.01 H2 and shows the destorted signals with an open loop in use as well as with a source related filter added to the last stage of the system it; follows that the measuring accuracy can not be improved due to a nonlinear circuit.The author has made a component of feedback circuit for the meter in question and taken a closed loop other than the former one; variation of gravitation is represented by the output of the feedback circuit;the electromagnitic force keeps the swing bar in a entire dynamic process of being balanced with an electric level of zero and thus the capicity balanced bridge of the closed-loop system takes the place of the former one, with a time constant of 2 sec..The improved circuit takes off the nonlinear effect and the recorded solid tide may show its extensive harmonic waves and an additional stable output of zero level which may give various data for the study of crustal defomation. seismic prediction and geophysics.

Key words: Gravity meter, Electromagntic feedback, Open(Closed) loop, Seismic prediction

摘要： GS-15型重力仪是利用摆杆位移大小来量度重力相对变化的精密仪器,摆杆位移是通过电容换能进行测量。由于该仪器为开环检测系统,而且系统的末级加接0.01Hz的有源滤波器,这样就失去了大于0.01Hz的高频成分,且使潮波产生相位失真,同时还存在着电路非线性带来的测量误差,因而测量精度难以提高。为此笔者对GS-15型重力仪加装了电磁反馈装置,将开环检测改为闭环检测,利用电磁力使重力仪摆杆始终处于零电平的动态平衡状态,以电磁反馈输出大小来度量重力的变化,这样就将开环检测系统改装为平衡电桥闭环检测系统,其时间常数为2秒。改装后,消除了电路的非线性影响,增强了系统的稳定性,记录的固体潮含有丰富的谐波,同时系统还增加了一路稳态零位输出,为地壳形变、地震预报和地球物理研究提供了波群丰富的资料。

关键词: 重力仪, 电磁反馈, 开环(闭环)线路, 地震预报