HR: 17:30h
AN: GP14A-06    [Abstracts]
TI: Deconvolution Of TEM Signals Using A Truncated SVD Approach
AU: * Helwig, S L
EM: helwig@geo.uni-koeln.de
AF: Institute of Geophysics and Meteorology, Univerity of Cologne, Albertus-Magnus Platz, Cologne, NRW 50923 Germany
AU: Lange, J
EM: lange@geo.uni-koeln.de
AF: Institute of Geophysics and Meteorology, Univerity of Cologne, Albertus-Magnus Platz, Cologne, NRW 50923 Germany
AU: Hanstein, T
EM: hanstein@geo.uni-koeln.de
AF: Institute of Geophysics and Meteorology, Univerity of Cologne, Albertus-Magnus Platz, Cologne, NRW 50923 Germany
AB: In transient electromagnetics (TEM) the influences of the measurement equipment and the transmitter current function on the measured signal are usually subsumed as system response. To interpret TEM data by means of inversion the system response is convolved with the synthetic transient before the deviance between synthetic and measured transients are calculated. This approach is preferred to deconvolution because of its numerical stability. To perform the mentioned convolution synthetic values must be calculated for times at least one decade prior to the times measured in the field. Whereas this is not a problem in 1D-inversions it becomes a problem in 2D- or 3D-inversions as the additional decade in time either slows down the forward calculations or even may cause instabilities in the calculation process. To avoid this problems the field data sets have to be deconvolved. As typical deconvolution techniques are proven to be unstable with TEM data we developed a stable technique based on the fit of a sum of exponential functions to the transients. The parameters of the fit build an over-determined linear system that is solved using a truncated SVD approach.
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting