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US Coast Guard Intends To Kill LORAN-C
adaviel writes "LORAN (Long Range Aids to Navigation) is an electronic navigation system using low-frequency radio, used by many boaters (including me) before GPS. It has an approximately 200m accuracy and is a functional replacement in case GPS fails or the US implements selective availability in time of war. The US Coast Guard, part of the Department of Homeland Security, intends to turn it off starting February 8." This is in spite of $160M spent on modernizing LORAN stations over the past 10 years.
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SA made GPS accurate to 10m.. With the "SA" feature disabled, you're down to 2m... And with Satelite enhancements, it's more like 20cm !
But that's irrelevant.. Because SA was intended to disable any enemy force from using GPS for accurate positioning - until they realized D-GPS (Differential GPS) made the whole point moot (you take a reference point - you send the signal to the receiver - And therefore - the receiver can deduce the SA introduced clock error - because now you have a ref point .. And believe it or not - it is a United Stated Uniform service - the US Coast Gard - that came up with it to overcome the artificially introduced uncertainty).
However, the military still keep exclusive use of the 1Mhz band (with the 10Mhz being public) - for the only purpose of being able to make real time measurements on tropospheric distortions - so - what happens - is that the military can make 1m accurate reading WITHOUT sat aids.
Actually, yes. When I was commercial fishing on a troller in Alaska we used Loran grid coordinates, spoken in Danish, to tell our brothers where the fish were. No one else could understand us. If we said "Over and out" the conversation was finished, but if we said "I'm off," that meant to change frequencies, tell how many King's you'd caught, and give the coordinates. Without the Loran our sneaky ways will have to be changed.
How about a moderation of -1 pedantic.