Military Surplus, Technostalgia

Before GPS There Was LORAN

LORAN Transmitter Bank

Near the beginning of WW2, the British developed a method of navigation using radio waves they called the GEE System. The GEE system transmitted radio “blips” from a master and two slave stations. The timing of the “blips” was fixed and maps were developed with hyperbolic lines showing the fixed time difference from a station. A receiver on board an aircraft could receive the “blips” and calculate the time difference between the master and two slave stations. The navigator would find the corresponding time difference lines, follow them until the two lines intersected, and he knew where he was.

GEE Transmitter

The US, being the innovators that we are, took that concept and expanded on it. By using a longer wavelength, the US-developed system was able to transmit further, up to 1200 nm. The US and Royal Navies used this system, called LOng RAnge Navigation, throughout most of WW2 and even into the 21st century. LORAN operated on a very similar concept as GEE. A master and two slave stations must be received with the time difference between the master and each slave measured a navigator can follow the hyperbolic lines on navigational charts to determine his location.

Nav chart of New York Harbor with the LORAN lines

LORAN takes this one step further, though, and organizes its transmitting stations into chains. Each chain has a known, fixed time delay between transmitting signals. The master station will transmit a series of blips, wait that amount of time, then transmit again. The secondary stations will receive the signal from the master then transmit its signals after a fixed amount of time. By doing this, the user will know which chain they are receiving and can actually use just the secondary signals in the event there is a problem with the LORAN system or their receiver.

After WW2, the US Coast Guard and Canadian Coast Guard were given responsibility for maintenance and operation of the LORAN systems in each country. These systems became the primary means by which ships and aircraft navigated. The LORAN technology was very straightforward, receivers were fairly inexpensive, and nav aids included the lines needed to figure out where in this big world you were. In fact, unlike the original GEE system, the signal strength from the transmitting stations was so strong that it was nearly impervious to jamming. Kind of important in times of war.

LORAN Station Malone, Malone, Florida

In 2010 LORAN in North America was put to sleep. With the rise of GPS and its hyper-accurate, global positioning and cheap receivers, LORAN was losing users. Its big drawback was that it didn’t cover the entire globe. Even with LORAN transmitters located along coastlines around the world, there were areas of the ocean that just could not be reached. GPS doesn’t have dead spots like LORAN, and the technology in GPS means it is nearly fully automated, and more accurate. So, by August 2010 all the LORAN transmitters in the US and Canada had been turned off. Let’s just hope the GPS satellites stay in orbit.

So, raise your glass of scotch to the radio towers of LORAN and join in thanking them for keeping our sailors and airmen on track. Then fire up the sat-nav unit in your car and find a liquor store to get more scotch.

[Image Credits: Public Domain, JM Briscoe]

  • Number_Six

    I hope they mothballed the equipment, rather than taking it all down. Satellite networks seems awfully fragile, especially when considering the absolute shit cyclone that would erupt should aliens or a solar flare knock them out.

      • Number_Six

        Suddenly tourism in Bermuda stops because "There be dragons".

      • Mr_Biggles

        Mrs_Biggles learned how to use the SEXtant when she did an ocean navigation course 10 or so years ago. They went from dead reckoning to sextant to GPS. I guess they felt that it was ok to skip LORAN.

        She doesn't see that the word is funny.

  • I do like the GPS (read: Google Maps) on my phone. However, I have a decent enough sense of direction to not need one in the truck.

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