利用菏泽地磁台二年半时间内198个地磁短期变化,首先用快速傅里叶变換法求出其离散傅氏谱,然后用最小二乘法得到其转换函数。分析表明,尽管转换函数在某种程度上受到计算方法引起的一定误差的影响,但1983年11月7日菏泽5.9级地震前后的异常变化是明显的。通过与某些干扰因素的相关性分析和统计检验认为,这一异常变化可能是与这次地震有关的前兆性变化。 Using 198 geomagnetic short-term changes in geomagnetic units over two and a half years in Heze, the discrete Fourier spectrum was obtained by Fast Fourier Transform, and then the transfer function was obtained by the least square method. The analysis shows that although the transfer function is affected to some extent by the error caused by the calculation method, the abnormal change before and after the Heze M5.9 earthquake on November 7, 1983 is obvious. Through the correlation analysis and statistical tests with some disturbing factors, this abnormal change may be a precursor to the earthquake.