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Old 01-30-2014, 02:24 PM   #165
Big red dog
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Joined: Jan 2005
Location: Adelaide, South Australia
Oddometer: 1,582
Originally Posted by Hoonatic Ty View Post
On the way out to the lookout I came across a strange aeronautical guidance device in the paddock. Naturally because it had a Danger High Voltage and other warning signs I had to take a closer look... I probably won't be able to have babies anymore, but may be able to communicate with a range of aircraft telepathically due to my exposure.

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As a nautical man, and proud Aussie, you might be interested...

This is a VOR/DME or VHF Omni Range beacon coupled with Distance Measuring Equipment. That one is probably the Point Lookout site, callsign PLO. It provides aircraft with their compass direction and distance from that ground station.

The direction function is a 1930s bit of technology. In the centre of that circle, an antenna is transmitting a VHF signal. Each of the little antennae surrounding it transmit with the sine wave shifted out of phase (eg the one due north will have 0 degrees phase shift, the one due east 90 degrees, and so on). The resulting composite signal is interpreted by aircraft equipment as a compass direction from the station (as opposed to even older, 1910s-era beacons which display direction TO the station). In the original systems this would have been achieved by an antenna rotating around the centre, like a radar, but this one is a modern solid-state one where each of those little domes takes turns to transmit.

The distance function, however, is a post-war Australian invention patented by AWA. It's basically a reverse radar: aircraft transmit a pair of pulses on the frequency nominated for this site, and measure how long the signal takes to return. This is interpreted as distance, although it is the "slant range" distance to the site, which depending on altitude, can be a lot longer than the distance over the ground.

Combined VOR/DME sites like this have a range of about 200 nautical miles and an accuracy between 25-100m, depending on altitude. They are being slowly allowed to fall out of repair as GPS becomes more prevalent.

Parking where you did, below the array and outside the fence, you're unlikely to have exposed yourself to much radiation, your boys are safe!
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