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2005 News Releases




Australian Optical Communications Record Broken in Tasmania

Date : 01 / 03 / 2005
Author : Chris Jones - VK2ZDD

Mike, VK7MJ on Mt Wellington and Chris Long on South Barrow have set a new Australian record for full duplex optical communication over a path of 167.7km using voice. The contact occurred between 1100 and 1200 UTC on Saturday, February 19, 2005. Two way full duplex voice communication was established at 475 TERRAHERTZ (that's right - visible light), over a distance of 167.7km between stations on the summits of Mount Wellington near Hobart and South Barrow, near Launceston Tasmania.

Both transmitters used current modulated 1W red Luxeon Lumileds into 200mm diameter fresnel lens, and they were clearly visible with the naked eye over the distance between the transmitters.

The signals were detected by silicon photodiodes at the focus of fresnel lens and a field effect transistor input amplifier. Signals going north were reported as strength 4 readability 7 with some scintillation and slow fading by Joe VK7JG, Jason VK7ZJA and Chris Long on Mt Barrow.

The signals received at Mt Wellington by Mike VK7MJ and Justin VK7TW were very noisy with signal strength 3 readability to 3. Despite this low signal level two-way duplex voice contacts were completed. This is certainly a record for Australian optical communications and probably a world record for non-laser communications.

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