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INTRODUCTIONIn the time domain electromagnetic (TDEM) method it has been common practice to model the current waveform of the transmitted signal, but the effect of the instrument transfer function has been neglected. In Effersar et al. (1999) it was shown that inverting TDEM data without taking into account the system transfer function in the forward modeling scheme lead to an erroneous description of the shallow part on the geophysical/geological model. The degree of error is very dependent of the near-surface resistivity of the model. High resistivity models leads to distinct but localized errors at very early time gates, whereas the effect from models with low to intermediate resistivities is "smeared" out over a larger time interval.