Signal processing concepts for airborne SIROTEM data

Abstract

Conventional stacking techniques are not generally suitable for airborne TEM surveys conducted at speeds exceeding 150 km/hr. For late channels (2?50 ms) linear stacking can be tolerated for up to 8 cycles representing lateral translations of 30 to 40 m accompanied by variations in coupling. The Nth root stack developed to reduce the effect of spikes in geophysical data can result in considerable distortion complicating the effects of sferics activity. Consequently other procedures are required including bandpass filters to compensate for bird motion, decay curve analysis, and spike rejection based on observations at a base station or predictive filtering.