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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.
Yes the real answer seems to be a complimentary system, that isn't owned by the US. Fortunately, people realized this and the Galileo project was born. After some initial hissing on both sides, the US and EU have worked it out so they'll be compatible, and a single receiver will be able to get data from both GNSS systems. That way should one be turned off, or break or whatever, the other still works, and when both are up it should be even more accurate.
Unfortunately, Galileo is being run by the EU who seems to be able to make the US congress look positively efficient by comparison. As such there are currently 0 Galileo satellites operating. The whole system was supposed to be online by the end of 2008, however now they are targeting having a single satellite up by the end of 2010.
Thus as it stands, the US still does have complete control over GNSS systems.
There is absolutely no use for Loran C. You currently have the following systems in place backing each other up. Many cheaper and better. In fact, many of these most likely will vanish soon.
1. GPS, LAAS, WAAS, DGPS
2. Galileo, EGNOS,
(as well as GLONASS and Baidu)
3. Inertial
4. Visual navigation (computer with terrain sensors, including sonar and radar)
5. Also VOR, DME, ADF, NDB, ILS, TLS, MLS, Marker beacon
with the final fallback
6. Old fashion navigation with compass, light houses, sextant, chronometer etc.
don't cut it off www.mgmbill.org
The U.S. is not the only country providing GNSS services. Russia has long had the GLONASS satellites; although their constellation has had some problems and does not currently provide 100% coverage over the globe (Russian coverage is at 100%, though, and I suspect U.S. coverage is near 100%.) Magellan makes commercially available GLONASS receivers, and I suppose others do as well. You can purchase dual GPS/GLONASS units, and the U.S. and Russia are in talks regarding bringing them to a common protocol so they'll be interchangeable if you have a receiver that picks up both frequencies. And the GLONASS program is receiving assistance from India, so there's more of an international approach to their program than just a Russian system.
I also know that China has their COMPASS satellites, but I don't know their status, or if there are commercially available receivers.
John
GLONASS has 16 operational satellites currently with 2 new birds coming online and one in the process of being decommissioned, they need 24 for full coverage. There are (expensive) commercial units with support for both GPS and GLONASS primarily targeted at surveyors because having the additional signals available makes very accurate (sub-meter) locks significantly faster. There are also commercial providers of GLONASS only units (Septentrio, Topcon, JAVAD, Magellan Navigation, Novatel, Leica Geosystems and Trimble Inc according to wikipedia) if you wanted them. The only reason the constellation will be back to full coverage is that the Indians pitched in a bunch of money to fly a bunch of the new birds. As of 2007 it has been official that the signals can be used for free by consumers in any country free of charge (not that they could stop you before since most devices don't need the L1 key to get accurate positioning, it just speeds things up).
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
Are you always this paranoid about the U.S. government? Seriously, the Russians have had their version of GNSS flying for 35 years, and you can buy a completely non-American GLONASS receiver that will give you the same data as an American (made in China, of course) GPS receiver. We know full well that we don't have a monopoly on global navigation.
They are shutting LORAN-C off because it's expensive to maintain a separate system, especially one that is not nearly as accurate as GPS, and is at risk of terrestrial attack (a determined terrorist group could easily destroy a critical LORAN-C tower, but the same group does not have physical access to the GPS satellites.) In addition, its consumers are not widespread, and are already using GPS for their primary navigation systems.
You should think before you make up bogus conspiracy theories. They make you look kind of crazy.
John
[...]Find a port when you're somewhere random in an ocean?
LORAN is pretty much useless for this. What almost everyone here seems to be missing is:
LORAN coverage is very limited.
There's e.g. none at all on the southern hemisphere, and in the northern it isn't much more than
a coastal navigation help either.
Have a look at the map.
LORAN is in no way a useful backup for GPS except in a very small part of the oceans.
Differential GPS made selective availability useless as a security tool.
No, DGPS is only useful if you have some way of of taking the pseudo-random variable offset recorded by the fixed GPS at the known point and sending it to the GPS you've stuck in the nose of your cruise missile or whatever. SA was a perfectly useful security tool. The real problems with it were twofold: First, the commercial applications for full-accuracy GPS were just too great to keep them locked up. Second, the military had such a difficult time procuring useful GPS units capable of accessing the encrypted full-accuracy signal that they gave up and acknowledged that most ground troops were walking around using commercial GPS rather than than the god-awful issue units and that they might as well have full accuracy.
If a job's not worth doing, it's not worth doing right.
The only people with anti-sat missiles are the same people who are operating the GPS satellites (the USAF); and the Chinese. (I suppose we can presume the Russians or Japanese could come up with something if they needed to, also.) And in both cases, the anti-sat missiles demonstrated were able to strike low earth orbit targets, in the range of a few hundred kilometers in altitude. GPS satellites are in medium earth orbits, which at 20,000km are considerably further away than any anti-sat missile ever tested has struck. Consider that the highest private rocket ever flown hasn't even reached orbit yet.
Detonating a nuke in space to disrupt communication is a video game plot device, not an actual strategy. It could theoretically disrupt or destroy nearby earthbound electronic chips, (taking out both GPS and LORAN-C receivers at the same time,) but at those distances even a big nuke would deliver little more energy to the satellites than a flashbulb. The birds themselves are separated from each other by distances of over 30,000 km, so even if your nuke got close enough to damage one it's safely distant from all of the others.
Space is really, really big. Mind-bogglingly big. These satellites are very, very safe right where they are. Not even James Bond could take out enough of them to be disruptive, but I'd suggest keeping a close eye on Chuck Norris.
John
Well if you were in the middle of the ocean, you probably wouldn't get a LORAN-C signal at all so your backup really isn't a backup. Check the LORAN-C coverage maps, anywhere outside the Caribbean, North Atlantic and North Pacific simply can't get any fix from LORAN-C signals (so if you're south of the equator you're probably SOL). Anywhere out of sight of coasts doesn't really get a great signal and has a fairly poor resolution.
http://en.wikipedia.org/wiki/OMEGA_Navigation_System
Thats what the Omega system was for. Operated from 1971 to 1997. For reasons unknown the USAR put me thru a correspondence course on the Omega system in like 1996 (1995?). Omega had worldwide coverage. Its interesting that Omega could be heard with those "ELF" receivers as the carrier frequencies were in the audio range, made it quite annoying to listen for "whistlers". Its interesting that LORAN relies on chains where a master TX sends a pulse, then the remotes send another as they hear the master, so each chain has a single point of failure. Omega on the other hand had each station send a different pattern of tones, so you'd sync to each pattern/station, then measure the relative time (and/or phase) difference between them to get the ratio of distances to each station, so no single point of failure. GPS is basically Omega with the following differences, about a zillion times higher frequency, a much fancier spread spectrum modulation than the four tone Omega, and of course the GPS satellites move...
http://en.wikipedia.org/wiki/Transit_(satellite)
The russian transit sat equivalents are still up there and transmitting as of a few years ago. All the systems generally transmitted two data carriers very close to 200 and 400 MHz. Receivers measured the ratio of frequencies, thus figuring out the doppler shift directly without needing an accurate oscillator on the ground. Doppler hits zero when the satellite is overhead, and its no great task to calculate and distribute plots of where a satellite is directly overhead at any moment. That gives you only one fix, but you can also measure the rate of change of the doppler effect, giving you quite accurately how high the satellite was above the horizon, that gives you a 2-D position.
"Science flies us to the moon. Religion flies us into buildings." - Victor Stenger