Influence of attitude change for time domain airborne electromagnetic system

The attitude of the receiver and transmitter coil of the airborne electromagnetic (AEM) system will be influenced by many external factors, which lead to a certain deviation of the measurement results. In previous studies, the processing methods of AEM data mainly consider the attitude change in frequency-domain. However, few of them focus on the complex situation of attitude change for time-domain AEM system. In this paper, we not only carry on a series of researches on angle change of attitude, but also improve the existing algorithm and take the coupling effect of coils and earth into account to study the influence of position change of coils by defining the two coordinate systems of attitude, we determine angle and rotation matrix of attitude change. Integrating the 1D layered semi-analytical solution with the change of angle and location, we derive the equation of attitude change of transform and receive coil. Additional, we taking the towed-bird separation system of helicopter as an example to analysis the arbitrary attitude change of the transceiver coil of time-domain AEM system. Moreover, based on the assumption of superposed dipole model, we provide the attitude correction factors which can be applied in practical work and improve the efficiency and precision of the measured data processing.