The observed changeof each signal as Cassini moved behind the rings provided a profile ofthe distribution of ring material as a function of distance fromSaturn, or an optical depth profile.
The transient electromagnetic method has a maximum depth because of continuous attenuation by transmission of electromagnetic signal in underground.
由于电磁信号在地下传播时不断衰减，瞬变电磁测深法有一个最大探测深度。
3
The improved smooth algorithm based on the characteristic sub-space used deepen the null to fall the depth, enhanced the system's signal to noise ratio.