
TY  - JOUR
A1  - Green, Andy 
T1  - Correcting Drift Errors in HEM Data
JF  - ASEG Extended Abstracts
JO  - ASEG Extended Abstracts
Y1  - 2003
VL  - 2003
IS  - 2
SP  - 1
EP  - 1
KW  - 
UR  - https://doi.org/10.1071/ASEG2003AB058 
N2  - Much HEM survey data suffers from low (spatial) frequency along-line variability in amplitude caused by slow changes in the system geometry and electronic drift. Even though the system is periodically taken up to a sufficient altitude to re-zero the primary field correction, the errors are not totally removed. This paper describes a procedure to reduce the effect of these errors. Each flight line is corrected by subtracting a slowly varying function of time that has been chosen so that the between-line differences over the whole survey area are minimized. The parameters of the correction functions are estimated using weighted, damped least squares. The procedure produces a marked improvement in the quality of the images of low frequency, in-phase channels that have been corrupted by drift noise. 
ER  -

