The Development of the TEMPEST AEM System

TEMPEST's origins lie in the difficulty half-sine AEM systems had in mapping the Australia's dryland salinity. This resulted in the development of the SALTMAP system, a collaboration between World Geoscience Corp and CSIRO. This was a 500 Hz square wave system with excellent high frequency response, full-waveform digital acquisition, processing, calibration and bird positioning. With the advent of the CRC for Australian Mineral Exploration Technologies (CRCAMET) and an industry push for an Australian system with deeper penetration, the SALTMAP System was taken to a lower base frequency (25 Hz) and higher power while retaining as much higher frequency response as possible. The previously implemented signal processing and calibration was retained enabling a reliable conversion to Step Response for ease of interpretation. The development history of TEMPEST is a result of collaboration between company, university and government research. Funding came from a diverse range of sources, government grants, collaborative industry funds and WGC. However, like most other fixed-wing systems, it was caught up in the consolidation and subsequent decadal changes in ownership that started after TEMPEST first became operational. But the consolidation was good for TEMPEST. At the end of 2000 it was operating on a platform that had limited power and an airframe that constrained the bird to a shape that made coil motion noise difficult to reduce. The merger with Geoterrex brought new aircraft, better coil suspension and extensive operational experience that took TEMPEST to another level of operational efficiency.