Can GPS fail? (and good, cheap GPS)

[Devonian]

- 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...?

There are no guarantees.

I use a pretty decent GPS system linked up to a small laptop with a SSD that is mounted on the dashboard in my Land Rover to navigate our way round the various green lanes etc, but we often have the situation where there is no GPS signal and we have to revert back to paper based maps, sometimes it can for 10 minutes, other times we have know it to be for several hours, so it is clearly not to do with geography as we cover large distances whilst out driving around.

[90.]

Hi,
Re-reading my previous post it comes across a little negative - not my intention sorry.!
anyway more for you to think about.

GPS accuracy relies on the number of satellites it can see at any one time, the more satellites the greater the accuracy.
My old garmin gps2 needed to see 4 satellites out of 8 (most it could see)to get a 3d position fix however go anywhere near trees, under cover or tall buildings and you loose your fix, and therefore your position and it could take a few mins to reacquire a new fix, if your stationary or slow moving no problem but in a car you could travel miles before it re-establishes a new position.

My modern GPS with an external "puck" antenna can see 12 satellites, more in the desert and gives me <10meter location this is it's ideal environment along with being at sea where you have unobstructed view of the sky, and crucially no landmarks where a map will show a best guess.

I use my GPS in conjunction with memory map in the UK & Europe when off-roading, this gives me an easy to follow graphical map with waymarks and routes I've setup. In the desert I use the GPS to give me a lat long fix and use this to give me a position on a map, or for countries with poor or non existant maps I use a fix on google earth images via pages I've printed out before leaving home - this takes some planning.!

The garmin etrex range is a great starter GPS, longer battery life than a smart phone and more accurate - it can use the US GPS system and the Russian GLONASS satellites, its worth having if you pick one up cheap - loads on ebay.! try and get one with a UK preloaded base map or you will need a map anyway to plot your location - learn how to use it and they can be very handy especially if you connect it to a pc.

Oh and don't rely on a smart phone poor battery life aside many(iphone excepted) use the cell mast and wifi system to provide a positional fix NOT a GPS satellite. this is why many don't work when there is no signal this is great in a city where the sky is often obstructed not so good in the highlands or mid wales.

regards
90

[Hamradioop]

GLA (General Lighthouse Authorities) is developing E-loran as a back up to GPS for shipping.


http://www.bbc.co.uk/news/science-environment-29758872
http://tech.slashdot.org/story/14/11/01 ... -in-the-uk


also the Military have regular GPS Jamming exercises so it is not a viable device in my view because when TSHTF the Jammers will go on.

[Waterbaby]

I'm not so great with technology anyway,so its always maps for me.
Surely you need to be able to charge these things anyway?

[Devonian]

I'm not so great with technology anyway,so its always maps for me.
Surely you need to be able to charge these things anyway?

Small hand held solar panel.

[rik_uk3]

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...?

GPS on phones should still work without a phone signal http://www.mcofs.org.uk/navigation-gpsa ... phones.asp

[Waterbaby]

Ah,I see!
Thanks Devonian!

[redskies]

Just because they should doesn't mean they will. And they're absolutely not suitable for doing things like climbing mountains - map and compass. That, btw, is coming directly from those who'd have to come and haul you off said mountains.

http://www.dailyrecord.co.uk/news/scien ... ps-1261343


As someone who is married to a member of the coastguard, these people drive me insane. I could list endless scenarios that have played out up here, where people who don't know the terrain, are unsuitably attired and who don't have the kit end up lost. Sometimes we find them, sometimes, we don't. And sometimes, when they're found, they're at the bottom of a 200m cliff and the only way to get them up is with rope teams and a bodybag.

And sometimes, it happens to people who do all the right things. But mostly, it has to be said, it's the result of 'operator error', and people who do not respect the geography.

[ForgeCorvus]

From Rik's link

Does this mean I no longer need a map and compass, or need to know how to read one?

No! Everyone heading into the hills needs to learn how to read a map, and to be able to navigate effectively with a paper map and compass.

Don't let technology replace thinking


GPS, Smartphone assisted GPS apps and Telephoney are great to help narrow down where you are, but you still need to be able to interpret your map in order to relate your route to the terrain.

As with all things, get the right tools for the job

[rik_uk3]

Don't shoot the messenger, I was just correcting an error from a previous post (that GPS won't work without a phone signal).

I'm a great believer in using map and compass, I'm teaching my six year old grandson to use them, but I have a place in my pack for a hand held GPS and my smartphone too.

NavFree is a free app which lets you download a complete UK street map so no phone signal needed, just GPS

https://play.google.com/store/apps/deta ... L&hl=en_GB