30 April 2015
The fascinating history of global navigation technologies includes the building of a radio antenna tower at Woodside, Victoria.
The construction of the Woodside OMEGA Tower was completed in 1978 and was one of eight towers positioned around the world.
The mast is Australia’s tallest man made structure (Wikipedia) and stands at 1,400 feet (427 metres) and was part of the now redundant OMEGA real time global navigation system which was switched off worldwide at exactly 0300 Zulu on 30 September 1997.
OMEGA was the first truly global-range radio navigation system, operated by the United States in cooperation with six partner nations. It enabled ships and aircraft to determine their position by receiving very low frequency (VLF) radio signals in the range 10 to 14 kHz, transmitted by a network of fixed terrestrial radio beacons. A receiver unit (somewhat bulky) receives the transmitter signals and displays data that can be used (with the aid of charts) to fix a position. It became operational around 1971 and was shut down in 1997 in favour of the Global Positioning Satellite system.
Very Low Frequency (VLF) was chosen for the navigation system as low frequency (long wave length) signals can propagate over very long distances following the curvature of the earth.
Although there existed other more accurate navigation systems (including the US TRANSIT satellite navigation system), until GPS was introduced OMEGA was the only real time system with global coverage.
OMEGA’s design accuracy was 2 to 4 nautical miles (3.7 to 7.4 km) compared to GPS which now provides accuracy to within a few metres and providing immediate LAT & LONG coordinates.
Why is it being demolished?
The decision to demolish the tower was instigated by the (then) Federal Member for Gippsland Daren Chester. Following the tragic death of a BASE jumper at the site 12 months ago. Mr Chester sought advice from the Department of Defence on the future use of the tower.
Tenders are being called for the demolition of the tower and the rehabilitation of the site. Interest will be high in the extensive grid of copper wire buried beneath the tower to create an equipotential ground (“earth”) base for the transmission antenna.
The final decision to demolish is subject to reviewing the tower’s heritage significance.
ABC Online - Australia's Tallest Structure to be demolished
Silicon Chip Online Article - “How Omega Ruled The World Before GPS” by David Maddison