Optimizing the SkyTEM Airborne System to 6.25 Hz Base Frequency Operation for Increased Depth of Penetration

Summary Within the Smart Exploration project SkyTEM has focused on the development of their airborne EM system in order to increase the depth of investigation. The developments for obtaining the increased depth of investigation have been twofold and focused on both the transmitter side and the receiver side. The developments on the transmitter side have focused on lowering the operational base frequency to 6.25 Hz. This leads to two benefits. Firstly, the on-time can be held for a longer time period inducing a higher signal in the ground. Secondly, it allows for off-time measurements to later times (~60 ms) leading to receival of signal from deeper levels in the ground. In order to measure the EM signal at a 6.25 Hz base frequency the noise level of the receiver system needs to be optimised for this operating condition. A validation survey was flown in June 2019 at the Blotberget Mine Site in Sweden. Data was successfully collected to the last gate located at ~60 ms with a high signal to noise ratio. The data collected validated the improvements made to the system in obtaining a higher depth of investigation. Hereby putting a novel deep penetrating airborne EM system to the market.