Implementation of low-cost, long-range microwave links on the Great Barrier Reef using evaporation duct transmission

This paper describes the implementation and subsequent performance of an over-the-horizon microwave link operating over seventy kilometres of ocean between the Australian mainland and Davies Reef, an offshore site within the Australian Great Barrier Reef. The outer sections of the Great Barrier Reef are not widely covered by cellular mobile networks with the only alternative being satellite telemetry, which becomes prohibitively expensive with high volume data such as images and video. A microwave radio link operating at a frequency of 10.5 GHz uses the ocean evaporation duct to propagate radio signals far beyond the optical line-of-sight limitation. While a ducted microwave link had previously been established at this site using commercial microwave equipment, the power requirements of this system proved to be unsustainable in the long-term. Advancements in technology for low-cost, Wireless Internet Service Provider equipment have allowed a system to be deployed which is both economical and has low power consumption, making it ideally suited for remote sites operating on solar power. Due to the lower cost of both the telecommunications equipment and the power system required, it now becomes feasible to deploy networks of monitoring stations linked by microwave systems taking advantage of evaporation duct propagation. The success of this link will open opportunities for high bandwidth linkages supporting a range of remote observation systems, including video, which will improve our understanding of this large complex eco-system.