Posted: 2/6/2011 12:34:21 PM EDT
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I apologize if this has already been talked about...I haven't spent a lot of time on this forum...
I was thinking about this the other day...if everything "hit the fan", would my handheld Garmin GPS still work? I'm not sure if the satelites that operate my GPS have to be maintained by someone or if they are self sufficient and maintenace free. Anyone know about this? |
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Quoted: .Gov maintains them. They have the ability to put error in or totally disable civilian users. Seems like I recently read that the EU put up their own sats, using another protocol. I wonder if we could use them here. Might be a good means of making sure you still had something if everything went wrong over here. |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? I don't think so, they used to have a 25m or so error in there for civilian users, that sort of thing. |
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Quoted: I don't think so, they used to have a 25m or so error in there for civilian users, that sort of thing.Quoted:.Gov maintains them. They have the ability to put error in or totally disable civilian users.
IN which case they could make the GPS lead the users in specific regions all go to the same places? That's what they told us way back when I was using an anpvs11. |
Purchase USGS Quad sheets for your area and any area that you might want to visit. More importantly, go out into the field and try and use them in a calm time before you have to use them 
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I guess a set of maps and a compass for your AO, will be a wise investment |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? No, nothing exotic like that, they just make your error go way up. They can't even block civilian users, since at least the older GPS receivers need the C/A signal before they can process the PPS (encrypted) signal. Remember each GPS sat just transmitts a single timing signal. Thats it. GPS sats are continually monitored by the USAF for both orbital and clock variations, and corrections are uploaded. No idea how long this will stay automated. It's probally safe to say the AF will be functioning longer post SHTF than other entities |
| GPS is great and I love my handheld and my car units, but navigating with map and compass will always be a skill that will be needed when times are worst...kind of like making fire. There are plenty of books that make it understandable, and many colleges offer map and compass courses in their non-credit offerings. |
Thanks for the input guys. Yeah, I love my Garmin handheld (Colorado 400T) with the 24k TOPO maps but figured it wouldn't be any good in that type of situation. I do have compasses and regular street maps...although it wouldn't hurt to pick up some nice topo maps. The one thing that I like about the maps on my handheld is that it shows all of the sources of water. Looks like I need to brush up on some old school orientation...got to think back to when I was a boy scout 
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? lol. I gotta hear more about this idea. / Google 'selective availability'. And these days there's a lot of ground-based GPS signal transmitters that help refine the accuracy of the signal. And a veritable constellation of the things in orbit. With a few more available at any one time as backups, both in orbit and on the ground waiting to be launched. IF a person is worried about the loss of a signal, they might consider deliberately buying a GPS that accepts and displays a variety of mapping data, so you'll at least have a wealth of maps and related info in a handy pocket-sized device. That'll still be useful even if the govt-supplied signal is deliberately fuzzed or dropped. |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? IF a person is worried about the loss of a signal, they might consider deliberately buying a GPS that accepts and displays a variety of mapping data, so you'll at least have a wealth of maps and related info in a handy pocket-sized device. That'll still be useful even if the govt-supplied signal is deliberately fuzzed or dropped. That's a good point...even if I don't get signal, I guess I stll have the maps. |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. Seems like I recently read that the EU put up their own sats, using another protocol. I wonder if we could use them here. Might be a good means of making sure you still had something if everything went wrong over here. As of a few years ago: The EU, Russia, and China were all developing their own GPS systems, and the US was developing a new one. The US wants everyone to use the same protocol so that satellites from any constellation can work together and increase the reliability of the whole system. Also, the US claims that our new system will be incapable of selective availability, and will not have a kill switch for disabling it for civilian use. The error offset of selective availability is an awesome weapon: imagine someone is dropping GPS guided bombs on you. Turn on selective availability and set the error to 1km east. Now all the bombs miss. |
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The error offset of selective availability is an awesome weapon: imagine someone is dropping GPS guided bombs on you. Turn on selective availability and set the error to 1km east. Now all the bombs miss. Cool, idea, but in no way related to GPS. All they can do is dither with the timing sources. Things like RAIM, WAAS, LAAS and DGPS (the first one is a monitor, the others ways of improving GPS accurcry) all will overcome this to some extent. |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? There is an M-code GPS signal, but the majority of troops that are using GPS have civilian units. Theoretically the .gov could disable all but the m-code signal. There is no way for anyone to make the gps signal "lead the users in specific regions." It's a unidirectional signal. Your GPS receiver merely uses the sat signals to triangulate your position. All the magic happens in the programing of your device. The internal software takes your coordinate location and places your location on a map. Quoted:
I don't think so, they used to have a 25m or so error in there for civilian users, that sort of thing. WAAS GPS coverage (currently only available in CONUS), has an average accuracy of <3 meters. I can easily tell what side of the street I'm walking on. The WAAS uses ground stations located throughout the country to provide correction codes based on weather conditions in the atmosphere and ionosphere. These codes are then fed back to two satellites and added to the basic GPS signal. Without the ground stations, the WAAS is useless, so you are stuck with DGPS accuracy. Typical DGPS accuracy is 3-5 meters. |
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WAAS GPS coverage (currently only available in CONUS), has an average accuracy of <3 meters. I can easily tell what side of the street I'm walking on. The WAAS uses ground stations located throughout the country to provide correction codes based on weather conditions in the atmosphere and ionosphere. These codes are then fed back to two satellites and added to the basic GPS signal. Without the ground stations, the WAAS is useless, so you are stuck with DGPS accuracy. Typical DGPS accuracy is 3-5 meters. WAAS is available in most of AK as well as the Caribbean . There are WAAS reference stations in San Juan, PR and Anchorage,Cold Bay, Bethal, Barrow, Juneau, Kotzebue, and Fairbanks. The these are treated exactly like CONUS stations There are also stations in Canada and Mexico, which I believe have been operational since 2007. Northern Canada and Northwestern Alaska will always have issues since WAAS is dependent on geostationary satellites. Average WAAS accuracy is ~1.5m. Worst case is 7.6m. The latter is a hard limit imposed on WAAS to allow it's use for GPS approaches. |
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.Gov maintains them. They have the ability to put error in or totally disable civilian users. IN which case they could make the GPS lead the users in specific regions all go to the same places? lol. I gotta hear more about this idea. / Google 'selective availability'. And these days there's a lot of ground-based GPS signal transmitters that help refine the accuracy of the signal. And a veritable constellation of the things in orbit. With a few more available at any one time as backups, both in orbit and on the ground waiting to be launched. IF a person is worried about the loss of a signal, they might consider deliberately buying a GPS that accepts and displays a variety of mapping data, so you'll at least have a wealth of maps and related info in a handy pocket-sized device. That'll still be useful even if the govt-supplied signal is deliberately fuzzed or dropped. Dude, SA got turned off a long time ago. New block GPS payloads don't even have it. |
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hmmm+
http://www.engadget.com/2011/01/20/faa-warns-of-ongoing-gps-issues-in-southeastern-us-due-to-defens/ this nocked out my XM radio the other night on the way home from work (i'm about as close as you can be to the zero point). |
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Guys,
This all boils down to dependency on a system, whether susceptible to GPS outage, EMP or whatever (my stance on both is a different topic). If you don't trust the system, then don't use it. Go analog/manual/whatever when required. Don't get caught in some kind of outage with your proverbial dick in your hand because you couldn't live without your GPS receiver. Get a lensatic compass, some topo maps, and learn how to use them. Better yet, strap on your BOB and take a hike and test all of your equipment. I might have a little more weight to lug because I don't depend on electronics, but I guarantee that my stuff will work. My .02. |