Design of frequency-domain controlled source for electromagnetic prospecting based on multi-frequency resonance
In order to overcome the low efficiency and poor resolution of the one-frequency-one-time frequency-domain electromagnetic (FDEM) method, a well-organized multi-frequency resonant network is presented to transmit a synthetized current with two or more frequencies. A low-frequency square pulse is used as the test signal to find the resonant frequencies, based on which the barcode driving signals are generated by the multi-frequency sinusoidal pulse width modulation (SPWM) method. The simulation results prove that the frequency leakage is reduced a lot and most of the energy is concentrated at the resonant frequencies. The resonant network and control technology is useful for obvious improvement of the sounding efficiency and resolution of FDEM method.