Dont Buy A GPS Unit

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John Fenna

Lifetime Member & Maker
Oct 7, 2006
23,137
2,878
66
Pembrokeshire
Aint got one - dont want one - map and compass and moss on the N side of trees for me!
Anyone got a sextant for swaps?
 

korvin karbon

Native
Jul 12, 2008
1,022
0
Fife
that story is BS. Read up on GPS, if it was really really in danger we would all know baout, mainly because you would have every plonker who needs their sat nav to get home, needing search and rescue to save them

GPS is a military system and designed to be rugged.
 

Mastino

Settler
Mar 8, 2006
651
1
61
Netherlands
Yeah, same story was reported here! Probably the clocks on which the system depends are starting to lose their synchronicity leading the systems to fail. Given their track record I suppose that a GPS failure due to the burocracy of the military is a plausible story. Therefore: always have a map & compass (in that order) and otherwise never assume that what the gizmo says is true...

BTW the military always have the option of playing with the so called 'programmed error', many GPS units give you an estimate of this programmed error. In the case of war or crisis, GPS units without a decoder (decoders only available to the military) will fail.
 

Nagual

Native
Jun 5, 2007
1,963
0
Argyll
that story is BS. Read up on GPS, if it was really really in danger we would all know baout, mainly because you would have every plonker who needs their sat nav to get home, needing search and rescue to save them

GPS is a military system and designed to be rugged.

Military kit....but the Paras broke it? :D


Isn't GPS an American Military thing? They rent out info for 'normal' use, and I think shut it down more than once..
 

GoatBoy666

Tenderfoot
Jul 27, 2005
96
3
53
West London
Korvin, strata-sphere.com is an intresting site.

My apologies for not checking the facts before posting,

kinda presumed the Guardian would have done its homework... :11doh:

I'll get my coat...:D

Goat
 
TBH, I thought that the GPS system used any satelite with a stationary position (above a fixed point on earth) to triangulate from - but I stand corrected.

That said, I used to have to plot GPS locations at different sites on a weekly basis for work, using a basic Garmin eTrex. What was interesting (obvious when you think about it) it would tell you how many satelites it was communicating with, tell you the signal strength for each, plot a little map showing their relative positions - and hence tell you the accuracy / margin of error of the reading (which ranged from around 12' to hundreds of feet.

To cut an already long burb short, this demonstrates that the GPS system will not 'fall over' if a satelite stops working, it will simply result in the receiver taking slightly longer to acquire other satelites and reduce the accuracy if it would have used the redundant one.

On some occasions, my GPS receiver would tell me it was communicating with up to 12 satelites - not bad if there's only 31 covering the entire globe !!!

(However, on cloudy days this could reduce to only 3/4.)

PS. If a satelite does breakdown affecting the accuracy, it will be quite funny watching all those reliant on their in car sat-navs suddenly reacting when the system tells them to take the turn they've just driven past - about as useful as SWMBO at map reading (but don't tell her I said that). :D
 

RAPPLEBY2000

Bushcrafter (boy, I've got a lot to say!)
Dec 2, 2003
3,195
14
51
England
loosing satelites? Pah that's nothing

Firstly you should never rely totally on a GPS, Know how to use a map!
I used to sell GPS's in 2 different camping shops, the amount of times they wouldn't work, had battery problems or had bad signals has convinced me never to buy one!

did you know the Earths magnetic poles can flip?(and it's many years overdue!)

If it does (which it has done many times before in pre history) then we're all in the poo!
because no one was around to see it even the scientists aren't too sure what will happen exactly.
I have a friend doing a PHD in space science and he's a bit worried about this!

(I would have used the NASA website but this one seems clearer)...
check this out:

http://www.halexandria.org/dward761.htm

copied from the section:Effects of Electromagnetic Surges on the Earth
The effects of massive solar fluctuations in the electromagnetic field can also influence life on Earth in other significant ways. For example, it is believed that extremely minute doses of magnetite in bacteria allow swimming bacteria to orient to the geomagnetic field. Similarly, homing pigeons, bees and termites are believed to use the same magnetite in conjunction with the geomagnetic field in the form of a navigational aid -- much as humans use compasses. Recently, researchers [21, 22] have found the mineral magnetite in human brain tissue, where it may represent part of a magnetic sensing system. The consistency of size, shape and distribution of the crystals has suggested that the magnetite has some biological function. In addition, such magnetite containing tissues may interact directly with weak magnetic fields.

Interactions of human or animal tissues with magnetic fields include the possible link of electrical distribution power lines with heightened cancer incidence and the onset of Alzheimer's disease [23]. In addition, there is increasing evidence that low intensity electromagnetic energy interactions might be fundamental to life processes, including the potential for therapeutic use [24]. Gregor Wieser [25] has conducted experiments with human subjects which suggest that changes in a magnetic field, rather than its mere presence, is the important factor; and that furthermore, weaker magnetic fields (such as the Earth's geomagnetic field) may be better at influencing the brain than stronger fields! The human immune system efficiency appears to particularly susceptible to fluctuating electromagnetic field (EMF) effects [26]. Obviously, a rapidly fluctuating geomagnetic field or a field reversal would have much greater effects on the human organism.

Just thought I'd give you something slightly more serious to worry about that will effect the whole world ;)

good night:rolleyes:
 
Isn't GPS an American Military thing? They rent out info for 'normal' use, and I think shut it down more than once..

Yes, they have shut i down over different areas a number of times. During desert storm they shut it down, but soon but it back up again because of all the civilian GPS units in the hands of us soldiers.

As I understand it the European system will work with old GPS receivers as well.

About GPS vs. maps, I think the biggest problem is your gps unit failing or running out of battery, not that us government cant look after their stuff. I view my gps as a compliment and I always bring a compass and map, if I'm unfamiliar with the terrain.
 

m.durston

Full Member
Jun 15, 2005
378
0
45
st albans
BTW the military always have the option of playing with the so called 'programmed error', many GPS units give you an estimate of this programmed error. In the case of war or crisis, GPS units without a decoder (decoders only available to the military) will fail.

i've seen this electronic trickery in action! all L118 light guns in the royal artillery run on a GPS system to help 'lay' the gun on target.
before leaving base we would have to get the crypto codes out to decode the real GPS signal otherwise the gun would think it was around a quarter of a mile away from its true location.
but like everyone says nothing beats ye olde mappe n compasse!
 

gregorach

Bushcrafter (boy, I've got a lot to say!)
Sep 15, 2005
3,723
28
51
Edinburgh
did you know the Earths magnetic poles can flip?(and it's many years overdue!)


"Overdue" is a pretty meaningless term here - yes, they happen on average every couple of hundred thousand years (over the last 10 million years) but there is a lot of variability and there have been periods when the interval between reversals has been much longer.

There is a great deal of debate about exactly how severe the effects could be. Some people think the Earth's magnetic field could more-or-less collapse, others think it will merely weaken a bit. However, since there is no geological or archaeological evidence (as far as I am aware) for severe adverse effects to life from previous reversals, I wouldn't get too worried on that score. The possibility of severe solar storms causing damage to power grids is another matter.

EDIT:

This page is pretty good on the subject:

Human beings have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals. Similarly, reversal patterns do not match patterns in species extinction during geological history.

Some animals, such as pigeons and whales, may use the Earth's magnetic field for direction finding. Assuming that a reversal takes a number of thousand years, that is, over many generations of each species, each animal may well adapt to the changing magnetic environment, or develop different methods of navigation.
 

Wallenstein

Settler
Feb 14, 2008
753
1
46
Warwickshire, UK
was the error not discontinued some time ago?
yeah, 10 years ago

wasn't that useful anyway, as if you have a fixed location (e.g. bunker) with a known accurate location you can work out the GPS error value and send an update to surrounding mobile GPS units

apparently it can be switched back on, but it would cause so much chaos with shipping / flights etc that it's pretty much never going to happen
 

Mikey P

Full Member
Nov 22, 2003
2,257
12
53
Glasgow, Scotland
I'm going to try and be as polite about this whole thing as I can:

It is uninformed nonsense​

All this talk about GPS failing or being turned off, or the Selective Availability function being reactivated. All. Absolute. Garbage.

The investment, in terms of time and money, technology, etc, and the various plans and upgrade programmes for GPS (for example, civvy aircraft instrument landing, etc) would suggest that GPS has a long term future and to claim that it is going to fail is causing unnecessary concern.

Galileo will come along and provide an alternative but you will not see the demise of GPS in our lifetime.
 

Bootstrap Bob

Full Member
Jun 21, 2006
407
9
52
Oxfordshire
wasn't that useful anyway, as if you have a fixed location (e.g. bunker) with a known accurate location you can work out the GPS error value and send an update to surrounding mobile GPS units

I agree, it's called differential GPS and something I used back in 2002 to map out the Nurburgring in Germany. I used an inertial navigation system (similar to fighter aircraft) with built in GPS and a fixed base station to correct for errors.

I think (but don't quote me on this) there are 24 geostationary GPS satelites around the planet and to get a fix on your location you only need 3 (ideally 4 to check the others for errors). This is why it's called triangulation;)

If they are to switch off some of these satellites I would expect them to do it gradually as to minimise any impact on existing systems but with so many available and in view of a point on the Earth's surface at any time you can afford to lose a few without too much trouble.

I haven't read the article myself but from what I hear I'm not getting too worried. By the way I always use a map anyway, I find it more satisfying :D
 

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