应用希氏变换估计地球介质电性阻抗

ESTIMATION OF IMPEDENCE IN EARTH'S MEDIUM BY HILBERT TRANSFORM

大地电磁测深中阻抗Z(f)满足希尔伯特变换条件。而常规阻抗估计用自功率谱有偏估计途径。当完全利用无偏功率谱相位估计,即通过希氏滤波瞬时谱分析直接估计张量阻抗时,理论推算可完全消除常规张量阻抗估计所导致的偏畸。逆归滤波前对其稳定性及误差密切相关的多项式B(z)的根b_z作指数衰减,而新导出的(?)(z)比原(?)(z)根远离单位圆。实际处理结果表明,其视电阻率曲线点值密集度及cp值均有所提高。

The impedence function Z (f) in MTS is fitted in the codition for Hilbert transform. But the conventional estimation of impedence is performed by means of self-correlation power spectrum biased estimation. When the uabiased estimation of power spectrum phase is entirely used, i. e, direct estimation of tensor impedence by Hilbert filter instantaneous spectral analysis, the theoretical derivation can entirely eliminate the distortion found in conventional estimation of tensor impedence. Before recursive filtering,the stability and the root bz of polynomial B(Z) which is closely related with error are exponentially attenuate, but the new derivative root of B (Z) is more far away from unit circle than original root of B (Z). The result of real processing indicates that the density of point on apperent-resistivity curve and CP values increase to some values extent.