Three Consequences of Removing the Primary Field from Airborne EM Data

P229 THREE CONSEQUENCES OF REMOVING THE PRIMARY FIELD FROM AIRBORNE EM DATA 1 R.S. SMITH Fugro Airborne Surveys 2060 Walkley Rd Ottawa Ont K1G 3P5 Canada Abstract In removing the primary field from fixed-wing time-domain airborne EM data the response is decomposed into the time-domain “in-phase” and “quadrature” components. The primary is approximated by the in-phase component which varies significantly as the transmitter-receiver separation changes. The quadrature component is purely a secondary response. In the off time the quadrature response is very similar to the total secondary response; however there are large differences in the on time and even some