Low-Frequency UAV SAM trials at Forrestania Electromagnetic Test Range in Western Australia

Gap Geophysics Australia (GAP) has been developing a UAV SAM receiver using its proprietary Total B Field magnetometer (TM7) technology. Conducting further system analysis at the Forrestania Electromagnetics (EM) Test Range, GAP has visited numerous times in the last decade. Past surveys included pedestrian SAM-EM and stationary SAMSON surveying with large ground-based loops, and Low Frequency HeliSAM (~2.083 Hz) all using the same Total B Field technology. This UAV survey is the culmination of 20 years of iterative development of the current generation total field technology. Throughout the course of the trial, GAP conducted several system tests, looking at the impact of varying flight speed on the sensor, UAV aircraft noise (using a hybrid of battery UAV), duty cycle and transmitter frequency as comparison to past surveys. Trials were primarily conducted at 50% transmitter duty cycle, 1 Hz for the bulk of the trial. One of the key aims of this survey was to robustly test the system for a commercial deployment. That meant critically analysing the viability of scaling up for large scale UAV EM surveying with grounded loops with both cost effectiveness and efficiency in mind. The GAP UAV SAM system is considered commercially ready for low frequency (1 Hz) EM surveys for industry. Based on the data collected, the system noise can be further improved, and sub 1 Hz frequencies are achievable.