Digital HF communications for autonomous instrumentation in the polar regions
thesisposted on 03.02.2012, 10:21 by Michael Prior-Jones
Autonomous instrumentation is used to collect scientific data in very remote locations, especially in the polar regions. Retrieving data from these instruments is often done by the use of satellite communications or by manual retrieval, the latter often requiring the use of an aircraft. This research focussed on the use of HF radio (i.e frequencies of 3-30MHz) as a cheaper technology for data communications in the polar regions and concentrated on three main areas of work: • the development of a channel simulator for high-latitude HF channels based on work by Warrington, Siddle and Stocker (2006) and using it for performance tests of existing HF modems • work on HF modem waveforms, including Polynomial Cancellation Coding OFDM (PCC-OFDM) and conventional OFDM, to try and create waveforms suitable for the more demanding high-latitude channels • an oblique propagation study using an OFDM waveform between Halley and Rothera stations in Antarctica, a 1600km sub-auroral link run for twelve months close to solar minimum. This work has shown that existing military HF modems (MIL-STD-188-110B) perform reasonably well in all but the most demanding high-latitude HF channels simulated. The oblique propagation study showed that a total annual data volume of around 400MB could be transmitted over the Halley-Rothera link, showing that HF can carry sufficient data to be useful for data retrieval. Data volumes were at their highest in the austral summer, but limited communications were possible year-round.