1. College of Geo-Exploration Science and Technology, Jilin University, Changchun 130026, China;
2. Department of Earth Sciences, Nanjing University, Nanjing 210093, China
Having investigated the design of classical FIR digital filter, the authors put forward a method of FIR filter design based on Chebyshev best uniform approximation which can be used to separate potential anomalies. In an experiment on the theoretical model, the maximum error of regional anomaly separation by low pass filter of Hanning window is 6.266×10-6 m/s2 , the mean square error is 2.115×10-6 m/s2, and the maximum percentage error is 22.2%. The errors are always higher than 10.1% when the computing points are beyond ±9 km. On the contrary, regional and residual anomalies separated by the best uniform approximation theory fit fairly well with the theoretical anomaly, with the curves in fairly good agreement. The maximum error of regional anomaly separation is 3.101×10-6 m/s2 , the mean square error is 0.989×10-6 m/s2 , and the maximum percentage error is 7.76% for several data on the boundary and is lower than 4.1% for the other points. The method was used to separate Bouguer gravity anomalies along the Sunwu-Jiayin profile with satisfactory results obtained. It is proved that the anomaly separation is quite complete.
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