
TY  - JOUR
A1  - Sattel, D. 
T1  - Improving conductivity models using on-time EM data
JF  - Exploration Geophysics
JO  - Explor. Geophys.
Y1  - 1998
VL  - 29
IS  - 4
SP  - 605
EP  - 608
KW  - 
UR  - https://doi.org/10.1071/EG998605 
N2  - Modelling of data from half-sine time-domain airborne EM systems is traditionally limited to the period following the transmitter turn-off, the off-time data. The joint use of on-time and off-time data widens the resolvable range of conductivities. Using a half-sine waveform with a base frequency of 25 Hz and a pulse width of 4 ms, conductivities and conductances as low as 0.5 mS/m and 0.02 S, respectively, become resolvable. Also, with the constraint of on-time data, automated modelling becomes more stable as noise at late time is less likely to be confused with signal. Conductivity-depth sections of QUESTEM-450 (Lane et al., ( 1998) data from Forrestania, Western Australia were modelled using a layered-earth inversion (LEI) and a current imaging technique. The known mineralisation, including massive sulphides and a banded iron formation, is indicated by the off-time data. For both methods, additional use of on-time data led to a model improvement. 
ER  -

