Dont Buy A GPS Unit

[Wallenstein]

Well, I've never had a map run out of batteries, for one thing...

8 March 2008, Brecon Beacon MR Log:

Call to search for a couple who [...] became disorientated in thick cloud and their map & compass blew away.​

I've never had my GPS get blown away in the wind


(I have sat on it and smashed the screen though!)

 

[Mikey P]

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.

Yep - you are correct: you need 4 satellites for a fix with altitude information.

They are always switching satellites off and graveyarding them - satellites have a lifespan and then they are usually replaced and retired. GPS have been replacing and retiring satellites for years - I think there have been about 5 blocks so far. Each block will have enhanced payloads and buses: for example, spot beams, better clocks, etc.

A certain number of spacecraft can be lost from orbit before the system starts to degrade. It would usually result in longer acquisition times rather than reduced accuracy. GPS are not geo-stationary and operate in LEO (Low Earth Orbit), so, they are constantly moving with respect to fixed positions on the ground. If you can't see enough, another will come over the horizon in 20 minutes!

I like maps and I like GPS - I am actually pretty good with both. Therefore, I have no issue with the use of GPS. If technology makes life easier, why not adopt it?

There are a number of enhancements to improve accuracy, like Differential GPS, eGPS and WAAG (which I think is now available outside the States), and the fact that the Civil Aviation Authorities are looking to mandate GPS-assisted landings makes a mockery of the original premise of this thread that GPS was 'fading away'!

Where do journalists get this rubbish?

 

[gregorach]

Where do journalists get this rubbish?

They just make it up down the pub. It's easier than actually working, and nobody important seems to mind. (There was at least one well-known "Eurocrats gone mad" story that was literally made up in a pub as a practical joke, but I forget which one...)

 

[stijnb]

oh no! now i will have to scroll all the way to where i am by myself with google earth on my phone instead of just wait till it's found my position:O

 

[Asa Samuel]

Guys! SHH! I'm trying to sell my phone which has GPS on it!

 

[jimford]

I lost my bearings in driving rain/sleet on the Cairngorm Plateau last year in July. I tried using my GPS, but the air temperature was around the 4 degrees C mark and because of that, the LCD display was black.

I needed to adjust the contrast so I could see the display, but couldn't because my hands were too cold owing to the windchill being -10. I used my compass instead!

Jim

 

[Goatboy]

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.

The "clocks" on the satellites are updated / corrected continually by the US millitary due to the effects of a whole host of things.
"The CONTROL segment consists of five Monitor Stations (Hawaii, Kwajalein, Ascension Island, Diego Garcia, Colorado Springs), three Ground Antennas, (Ascension Island, Diego Garcia, Kwajalein), and a Master Control Station (MCS) located at Schriever AFB in Colorado. The monitor stations passively track all satellites in view, accumulating ranging data. This information is processed at the MCS to determine satellite orbits and to update each satellite's navigation message. Updated information is transmitted to each satellite via the Ground Antennas. "

http://tycho.usno.navy.mil/gpsinfo.html

And as mentioned else where on the thread the US recieve payment and has a responsibility to keep it that way unless we want the whole "planes falling out of the sky" and a plethora of other related problems occuring.

Cheers
Goatboy

 

[neilwf]

There are too many systems military, and civilian, seen and, unseen relying on the GPS satellite system for it to stop working. BTW I don't think the satellites are geostationary. I'm sure I read that on the website of the US govenment body responsible for them.
Anyone who strays from the beaten path must be able to read a map and use a compass, I've been doing it since my DoE award days. However with the cost of a basic GPS unit (the ones that just give a grid reference) surely it's worth skicking one in you pack just in case!

 

[Mikey P]

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.

Yes but it's now based on spot beams. You are not affected unless you are in the area selected for reapplication of 'Selective Availability'. It is not a blanket change across the globe.

BTW I don't think the satellites are geostationary. I'm sure I read that on the website of the US govenment body responsible for them.

Correct, they are LEOs (low earth orbiters). Can't remember what the period is, something like 8 hours. The wouldn't work as geostationary or geosynchronous - signal would never be received at the earth's surface as it's too far away.

Now, if you want to get really technical guys, let's talk GPS jamming.....

....or then, maybe let's not.

 

[akabu]

Guardian do a fact check? you most be kidding ships, planes, trains, trucks, cars most have the same system.
They are 12 Sat's plus Back up's [you only need 3]
When the USA shut it down was to keep the Bad guy's from using it. the non mil. use is good enougth the USA Mil. version can put a guided bomb up the Bun^ hole.with less civi's hurt.
Compass ...Alway's no Batt's or someone else in control

 

[HillBill]

The date 2010 given for the faliures is interesting. NASA decommision their fleet then, they can no longer repair anything in space. Basically giving it all up. Whys that then? Why would NASA abandon everything it has ever done?

http://londonist.com/tags/nasa

http://forum.nasaspaceflight.com/index.php?topic=640.0

http://www.nasaproblems.com/

To those who think it will never fail, don't put money on that. the satelites are abandoned as of 2010

 

[Humpback]

Date: Sept. 16 +
Mission: STS-134
Launch Vehicle: Space Shuttle Discovery
Launch Site: Kennedy Space Center - Launch Pad 39A
Launch Time: 1 p.m. EDT +
Description: Space shuttle Discovery will deliver an EXPRESS Logistics Carrier-3 (ELC-3) and an Alpha Magnetic Spectrometer (AMS) to the International Space Station.

Taken from the 2010 NASA flight schedule at:

http://www.nasa.gov/missions/highlights/schedule.html

Must be shutting down in October then.

"To those who think it will never fail, don't put money on that. the satelites are abandoned as of 2010"


I'll put money on it and take a £10 bet with you Hillbill that GPS is working as at 31st December 2010. Money to Help for Heroes - How about it a no lose situation?

Alan

 

[HillBill]

Date: Sept. 16 +
Mission: STS-134
Launch Vehicle: Space Shuttle Discovery
Launch Site: Kennedy Space Center - Launch Pad 39A
Launch Time: 1 p.m. EDT +
Description: Space shuttle Discovery will deliver an EXPRESS Logistics Carrier-3 (ELC-3) and an Alpha Magnetic Spectrometer (AMS) to the International Space Station.

Taken from the 2010 NASA flight schedule at:

http://www.nasa.gov/missions/highlights/schedule.html

Must be shutting down in October then.

"To those who think it will never fail, don't put money on that. the satelites are abandoned as of 2010"


I'll put money on it and take a £10 bet with you Hillbill that GPS is working as at 31st December 2010. Money to Help for Heroes - How about it a no lose situation?

Alan

It is a good cause. I'm game. They will all be knocked out of the sky with the same solar storms that will kill the grid. it is inevitable and they know it.

No point flogging a dead horse. maybe thats the last scheduled mission. They are shutting the shuttle fleet down though. The only ones capable of repairing anything. Maybe the gps will still work after 2010 but only until they expire without repair or maintenance

 

[woodlanduk]

Well, I've never had a map run out of batteries, for one thing...

funny that nor has my GPS :0)

 

[woodlanduk]

Hey everyone, was jus surfin on the net and found this...

http://www.guardian.co.uk/technology/2009/may/19/gps-close-to-breakdown

Hmmmm...............doesnt sound to good for all the GPS users out there.

Maybe map sales will be on the increase soon me thinks...

Keep your compass cheaper than $2 bill a year...

Goat

LMAO i read some of the replys,holy S**t..... guys you all worry too much about nothing.so ya sat nav dont work when your on the hills,you have eyes and ears ,your all trained in natural navigation and you know never to trust 1 compass which is why you take 2.. and if you looked where you were going you shouldknow your way back as for getting lost in the UK if you do...well you shouldnt be let out without adult supervision..

 

[Minotaur]

I thought we were going over to the European system anyway, and is it not an improved system?

If you read how the US Military use GPS there is no way they are letting GPS go.

 

[alecf]

I found myself ontop of Carnedd Llewelyn in thick fog following a GPS I had been given to find some people on the summit. Spent half an hour looking for them with this thing untill I put it down and found them in 2 minutes flat with the compass and map...

We found out later that somehow this thing was reading about a km off even though it said accurate to 5 metres at the time...

I won't be using one of them again!

 

[apj1974]

But I need my GPS for geocaching!

 

[gunnix]

A GPS unit is nice and easy but can fail.. So in a group take two GPS units, easy solution. I don't believe the GPS system will crash anytime soon...

Maps are reliable, and should be at hand in cars or ships which use GPS as well.

In remote expeditions you take maps and then a GPS to make life easier, life depends on the ability to navigate so map and compass comes along.

Sure if you have the ability you can do fine with only a small undetailed map, or no map at all and still make a long trip, as long as you have a plan and different features memorized. Navigate using hints from nature. Like in the old days...
Some guy sailed around the world without any navigational instruments...Marvin Creamer. Listen here: http://www.furledsails.com/article.php3?article=774

 

[Carbuncle]

I found myself ontop of Carnedd Llewelyn in thick fog following a GPS I had been given to find some people on the summit. Spent half an hour looking for them with this thing untill I put it down and found them in 2 minutes flat with the compass and map...

We found out later that somehow this thing was reading about a km off even though it said accurate to 5 metres at the time...

I won't be using one of them again!

The year before last I was stood on Pen-y-cloddiau, doing resections (I had treated myself to a mirror compass, and was curious how accurate I could get) while may fellow walker had nipped off to relieve himself (some kind soul had dug concentric ditches around the hilltop seemingly for this purpose ;-))

Anyhow, I was scratching my head since I was way off, and I was looking at very clear landmarks (e.g. the radio mast to the north). I did a bit of digging when I came home, and, though I can't find the references now - if they were on the web - it seems there are magnetic anomolies there caused by the rock formations.

Point being, GPS's fail, compasses fail, each has its constraints, and for the most part they're complementary. Compasses degrade functionally in low visibility, GPS's without a decent view of the sky. The argument "Map and Compass v GPS" has always been a red herring, "Map and Compass v Map and GPS" is fairer, though I'm sure many carry all three. I'm speaking as a compass man (though I often hang a GPS off my rucksack for logging/backup), my preference is really down to the fact that compass navigation is more pleasurable, you're constantly refering to your surroundings.