Can GPS fail? (and good, cheap GPS)

[CynicalSurvival]

I was wondering if anyone knows whether GPS could fail during an emergency situation? Presumably the satellites have their own power supply, right? Is it infallible?

And then, assuming that I can rely on it to a reasonably good extent, I'd like to add a good, small, cheap-as-poss GPS to my GHB or perhaps even to my every day carry. Was thinking of picking this one up (not necessarily from amazon but it's useful for the reviews...) http://www.amazon.co.uk/ChannelGoods-Po ... ywords=gps

If anyone has a better suggestion I'd appreciate it. I have never really learned map&compass skills, though I included a local map in my GHB.

[Devonian]

Yes they can fail and also the US can (and have in the past) simply turned off the non-military GPS signals.

So no you cannot rely on GPS when you are likely to need it the most.

[StashCache]

Pretty much infallible I guess yeah. I was however entertaining this idea a few weeks back though. I love GPS and who doesn't, it's great for going for a random ramble and finding your way back even if you don't know the area. Fantastic for leaving waypoints of potential BOL to come back and investigate later, or even places of natural food supply, streams and rivers for water, and even where you have left caches. But you might want to back that up with details on a physical map because if you do have trouble you need to know where things are, if you can't remember fully then you're screwed.

The only things I could come up with that would be bad, apart from actual device failure, would be a Coronal mass ejection from the sun, which I guess could have the potential to knock out satellites if strong enough. No doubt we would be well informed about the possibility of an event like this before it happened though. Then the possibility that whoever is in control of the satellites can just simply shut them down and deny anyone using them.

The other event I thought about would be the same as you stated, the possibility of something happening at ground control and it being left unmanned or without power. After some research I found someone stating that according to the book in this link, they reckon that a satellite would probably go out of commission after about two weeks without intervention from ground control. I imagine they are constantly tweaking it's orbit path, synching time and position, uploading updates and such like, and without that it seems they would be useless fairly quickly.

Link to the book that some guy pointed to that had this research in ...

http://books.google.co.uk/books?pg=PA21 ... edir_esc=y

[CynicalSurvival]

Thanks guys for that info.

I also found this link - it is from back in 2003 but interesting statement on how much of our tech and industry relies on GPS continuing to function, and the consequences if it went down (if anything, likely to be an even bigger issue today...?)
http://archive.wired.com/wired/archive/ ... .html?pg=6

I agree StashCache that GPS is awesome but as you say, a paper map as backup would be the best idea. Do use GPS coords to hide caches of supplies atm?

ADDED: sorry forgot to put in the link first time around!

[StashCache]

It is mad when you think about all of its uses, I'm pretty sure I saw something a while back about a combine harvester that practically ran itself using GPS.

I haven't actually used any coords to cache anything yet but I'm preparing to do so and intend to. I've only really been using GPS so far just to make notes on good spots to bug out and various waypoints of interest around sites. I do a bit of geocaching for fun though as well which can be amusing.

I intended to have the GPS/batteries/solar charger in a bug out situation with many potential locations in it in case people where already around my preferred spot then I would have back ups. I also intended using it for hidden caches in multiple spots so I could always have some back up supplies and kit around and that's what got me thinking about some sort of failure.

I do think it would be fine the majority of scenarios and pretty foolproof but I'm glad I thought it through the other week and can back it up with maps now just in case.

[90.]

Hi, GPS is not to be relied on as your sole means of navigation, the biggest problem with the widespread use of tomtom's etc is people don't pay attention to the journey's route, landmarks etc.
You would be well advised to learn how to at the very least read an OS map and then learn to navigate from it.
Once you can do this you can make your own maps for your caches or routes and they will only be known to you, whereas OSGB ref's or lat/long can be found by anyone with google earth.

As said the GPS signal can be made less accurate by removing selective availability(SA) this gives accuracy to about 10m, without SA its about 250m not good enough to pick up road junctions.
The GPS signal can also be forced into inaccuracy by the USAF by simply changing the satellites time sync, this was done on the eve of the Iraqi invasion to screw up the Iraqi targeting while the US and others used a DGPS signal to restore accuracy to their GPS units.

I have a few gps units from the 1st magellan & garmin gps2 units to the latest sat navs but love maps and the information they can provide google Earth is also fantastic tool for scouting locations and BO routes
GPS-handy tool but don't rely on it.

regards
90.

[Malthouse]

As said above, the US can reduce the accuracy for none military applications. The satellites are also vulnerable to solar activity, much more so that terrestrial electronics. The weak radio signal can also be jammed very easily by transmitting on the same frequencies, more sophisticated attacks can add in a malicious error without the user ever knowing.

So in short, GPS is fallible! Great to use as an every day aid, but keep up your compass and map reading skills.

[Hamradioop]

I agree with 90 and Malthouse. I regard them as unreliable and prefer a map.

[redskies]

I'm with the map and compass brigade. For a few reasons.

1) Tech can and does fail with monotonous regularity

2) If SHTF, then the chances of things like GPS surviving and being available are pretty slim.

3) It's NOT reliable when you're out in places like Snowdon or the Cairngorms; there are far too many idiots trying to navigate their way round places like that, where signal strengths aren't reliable, using GPS apps on mobile phones. Not only is it potentially fatal to you, you put at risk the teams who have to come and rescue your stupid self.

Map and compass. GPS is nice, but should not, ever, be relied upon, particularly in difficult terrain.

[CynicalSurvival]

It's NOT reliable when you're out in places like Snowdon or the Cairngorms; there are far too many idiots trying to navigate their way round places like that, where signal strengths aren't reliable, using GPS apps on mobile phones. Not only is it potentially fatal to you, you put at risk the teams who have to come and rescue your stupid self.

- Thanks, I already knew that GPS on mobile phones failed when there is no signal (I regularly go to Scottish islands where the phone signal sucks) but didn't know that applied to hand-held GPS devices too, don't they work anywhere...?