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"Pathfinders" Take Shape For Galileo, Europe's GPS

kdawson posted more than 4 years ago | from the dodging-the-space-junk dept.

Space 105

oliderid sends along a BBC report on progress toward Europe's home-grown GPS system. The Galileo concept will get an initial test via four "pathfinder" satellites that will be the first in the Galileo constellation. Galileo is intended to be complementary with the US GPS system — when all 30 Galileo birds are flying, a receiver with both GS and Galileo capability should enjoy 1-meter positional accuracy, vs. the several meters available through GPS alone, according to the article. There's a video tour of the facility where the pathfinders are being built. "After all the wrangling, the delays, and the furor over cost, Europe's version of GPS is finally starting to take shape. Due for launch in pairs in late 2010 and early 2011, the 'pathfinders' will form a mini-constellation in the sky. They will transmit the navigation signals that demonstrate the European system can become a reality."

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105 comments

fp (-1, Troll)

Anonymous Coward | more than 4 years ago | (#30108662)

eat my asshole you cocksucking faggots!

I'm Tucker Max and I always win.

The EU system won't get used (-1, Troll)

Anonymous Coward | more than 4 years ago | (#30108872)

GPS is so standard now, and it is bugfree. It's hard to imagine anyone switching.

Re:The EU system won't get used (5, Funny)

Anonymous Coward | more than 4 years ago | (#30108950)

GPS is so standard now, and it is bugfree. It's hard to imagine anyone switching.

Yeah, "complementary" is a long word, isn't it? I wonder what it means.

Re:The EU system won't get used (0)

Anonymous Coward | more than 4 years ago | (#30113662)

Hello,

It's not just a GPS replacement. It has more accuracy for civil users, and it has integrity, which is very important for flight traffic. It will guarantee that your received signal is true.

Additional services for emergency and rescue are also implemented in the Galileo signals.

Best Regards,
Carlos

Re:The EU system won't get used (1, Insightful)

Anonymous Coward | more than 4 years ago | (#30108952)

It seems you can use it as a quality-enhancing addition to GPS instead of a replacement - that might help.

Re:The EU system won't get used (1)

Arimus (198136) | more than 4 years ago | (#30109240)

Assuming the US stick to their promise to keep SA turned off...

The whole point of the EU system during normal use is not to REPLACE GPS but act as a ADDITIONAL aid which should improve accuracy.

Of course only America matters and the rest of the world doesn't...

Re:The EU system won't get used (0)

Anonymous Coward | more than 4 years ago | (#30109964)

True, only American matters, since we determine everthing in the world, from the economy to what's hot in music. Hell, were even the best typists.

Re:The EU system won't get used (2, Informative)

Seraphim1982 (813899) | more than 4 years ago | (#30111098)

[quote]Assuming the US stick to their promise to keep SA turned off...[/quote]
Well, turning on SA would screw airplanes everywhere, and new GPS III satellites aren't going to have SA (this was announced in 2007 so it may have already started), so it is pretty hard to not keep their promise.

Re:The EU system won't get used (1)

TheTurtlesMoves (1442727) | more than 4 years ago | (#30113374)

Well, turning on SA would screw airplanes everywhere...

No it wouldn't. How the hell do to you think they flew planes around in the 80's. Do you really think the only navigation device on a plane is GPS? Furthermore they usually have (commercial airliners at least) military grade GPS and SA won't disrupt them. Finally what the hell are pilots for?

Re:The EU system won't get used (1)

molecular (311632) | more than 4 years ago | (#30114038)

The whole point of the EU system during normal use is not to REPLACE GPS but act as a ADDITIONAL aid which should improve accuracy.

Of course only America matters and the rest of the world doesn't...

I always thought the point of Galileo was to have a positioning service that is not controlled by the military. NAVSTAR-GPS is american military, GLONASS russian military.

Re:The EU system won't get used (0)

Anonymous Coward | more than 4 years ago | (#30109352)

It's the first step on the European plan of invasion. They can't rely on the GPS to invade the USA so they build their own.

Re:The EU system won't get used (0)

Anonymous Coward | more than 4 years ago | (#30109450)

Shhh, plan GIANT OCTOPI was supposed to be secret.

Re:The EU system won't get used (0)

Anonymous Coward | more than 4 years ago | (#30109900)

If they wait a few years they'll be able to buy it from the chinese for just pennies on the euro.

Funding (2, Interesting)

lazylocomotives (1645339) | more than 4 years ago | (#30108748)

How are they getting funding? As recently as yesterday I was reading about how it was pretty much an orphaned project because no one wanted to buy what was already available for free (albeit less reliably). I skimmed TFA and found nothing on the matter. No matter how they funded it (unless they sold some babies or something), I'm glad they are moving forward on this. I see this as being really good for Europe, and the space industry in general.

Re:Funding (3, Funny)

Anonymous Coward | more than 4 years ago | (#30108784)

(unless they sold some babies or something)

Don't be so narrow minded. Music industry execs have to eat something.

Re:Funding (0)

Anonymous Coward | more than 4 years ago | (#30109246)

(unless they sold some babies or something)

Don't be so narrow minded. Music industry execs have to eat something.

Let them eat cock!


... we're fresh out of cake.

Re:Funding (1)

daem0n1x (748565) | more than 4 years ago | (#30113756)

Don't forget Europe is a lair of faggie, liberal, nanny-state, tree-hugging, pot-smoking, smelly-hippies commies. Everybody knows commies have babies for breakfast.

Re:Funding (1)

RockDoctor (15477) | more than 4 years ago | (#30123210)

Don't forget Europe is a lair of faggie, liberal, nanny-state, tree-hugging, pot-smoking, smelly-hippies commies.

Huh, whuzzat? you calling me?

Everybody knows commies have babies for breakfast.

Yeah sure. Lightly fried in hash oil. Can't beat them. Well, shouldn't have to ; should be tender enough already. But that last shipment of babies which you sent - good capitalist pig that you are - was decidedly below standard. Tendons all stringy, guts not properly hosed through. Really poor stuff. If you don't get your baby kidnapping business together and improve your quality control, we'll go to another supplier.

Re:Funding (3, Informative)

Zoxed (676559) | more than 4 years ago | (#30108874)

> How are they getting funding? As recently as yesterday I was reading about how it was pretty much an orphaned project because no one wanted to buy what was already available for free (albeit less reliably).

I can not remember the full story, but the industry funding arguments dragged along for years, and in the end the EU took over funding of the project (it was too high profile to fail !!).

http://en.wikipedia.org/wiki/Galileo_(satellite_navigation) [wikipedia.org]

Re:Funding (3, Informative)

Ethanol-fueled (1125189) | more than 4 years ago | (#30108934)

Also, China and Russia have plans to develop their own GPS systems as well. This [csmonitor.com] indicates that there is plenty of squabbling behind the scenes.

Re:Funding (2, Informative)

mirix (1649853) | more than 4 years ago | (#30109184)

Russia already has one, GLONASS [wikipedia.org]

Re:Funding (1)

peragrin (659227) | more than 4 years ago | (#30110608)

of course Glonass only works over russia. it is a little thing but I think it is important.

Re:Funding (3, Informative)

mirix (1649853) | more than 4 years ago | (#30110732)

No, it covers almost all of earth. A few years ago you would be more correct though.

It's short a few satellites for whole world coverage right now. Now that Russia has oil dollars running in, the whole world should be back up in a year or so... they've been launching satellites quite frequently the last few years.

Here is a map of current coverage.. basically everywhere except Antarctica.
map [glonass-ianc.rsa.ru] A few pieces are missing here and there, but it's a far cry from "just russia".

Re:Funding (2, Interesting)

Anonymous Coward | more than 4 years ago | (#30108978)

Funding ? Well, in the Netherlands our government just decided to implement variable road taxes. All cars will get a GPS box that registers where you drive, and at what time, and it will automatically send that data to the central government servers.
The amount of money involved in this taxation plan alone would make it financially feasible to put a complete GPS system up there.

Of course security related government agencies will also have full access to the database as well. Believe me, it will get funded.

Re:Funding (2, Insightful)

YrWrstNtmr (564987) | more than 4 years ago | (#30111212)

Funding ? Well, in the Netherlands our government just decided to implement variable road taxes. All cars will get a GPS box that registers where you drive, and at what time, and it will automatically send that data to the central government servers.
The amount of money involved in this taxation plan alone would make it financially feasible to put a complete GPS system up there.


Excellent. Bring in a system to monitor every movement, and make the citizens being monitored pay for it.

Re:Funding (1)

molecular (311632) | more than 4 years ago | (#30114070)

Of course security related government agencies will also have full access to the database as well. Believe me, it will get funded.

Also in germany this is on the way. About time, 1984 is overdue and we need more security from terrorists, child molesters and other scum. Also we can then more easily fine for speeding. And all this on a european scale. Brave new world!

EU Vehicle Tracking Plan (3, Insightful)

Dr_Barnowl (709838) | more than 4 years ago | (#30109270)

They are getting funding from the government.

1) They want to track all vehicles in the EU. Galileo is designed to have much better performance in urban areas than GPS.

Proposals were on the UK Department for Transport website which detailed the desire to place a satellite positioning tracker with a cellular modem in every vehicle, by law, for the alleged purpose of "road pricing" ; charging for transit on key congested roads at certain times. Road pricing is horseshit because if having to drive on a congested road isn't sufficient deterrent to stop you doing it, then taxation isn't going to achieve it. You could also achieve the same goal much more cheaply with a mandatory active RFID numberplate and a pickup loop on these "key" roads, so Occams razor says that they want something that doesn't just track your use of certain roads.

2) Military reasons

Let's face it. Would you want your military dependant on a system that a culture of well known isolationists who live half a world away can switch off at their whim? Neither would I. Independance from US control is the second motivator.

Re:EU Vehicle Tracking Plan (0)

ZackSchil (560462) | more than 4 years ago | (#30109300)

If the US switched off GPS, then we wouldn't have GPS either. Plus, there's not a chance any first world nation would ever wage an actual war with another. The stakes are way too high.

Re:EU Vehicle Tracking Plan (1)

Beretta Vexe (535187) | more than 4 years ago | (#30109408)

They will not switch off the GPS signal, they will switch it to encrypted US military device only signal.

Re:EU Vehicle Tracking Plan (2, Informative)

ptbarnett (159784) | more than 4 years ago | (#30109896)

If the US switched off GPS, then we wouldn't have GPS either.

GPS is not "switched off". Instead, "Selective Availability" (SA) is turned back on.

SA introduces random, unpredictable errors into the unencrypted signals broadcast by the GPS satellites. As a result, the accuracy of a position decreases. When the GPS system first went online and SA was still enabled, typical position accuracy was about within 10 meters:

http://en.wikipedia.org/wiki/Global_Positioning_System#Selective_availability [wikipedia.org]

SA can still be enabled (introducing errors up to 100m), and can be enabled for only certain parts of the globe. But, it only degrades the unencrypted broadcast. The encrypted signal used by the military is not affected.

Re:EU Vehicle Tracking Plan (0)

Anonymous Coward | more than 4 years ago | (#30109982)

SA is one option. It is intended to make things such as cruise missiles based upon it somewhat useless (unless they carry nukes, which is increasingly likely, and there +/- 100m makes no difference at all).

Turning off the unencrypted signal is another option. In that case, your GPS receiver becomes useful only as a paper weight.

If/when TSHTF, don't believe for one second that they will hesitate to turn off the encrypted signal, and if any aircraft or ships go down in the process ... well, that's just collateral damage.

Re:EU Vehicle Tracking Plan (4, Interesting)

thogard (43403) | more than 4 years ago | (#30110466)

SA was a hack on the early systems and the newest sats don't have that ability at all. The SA adjuster on older sats is a motor driven thing and it has been broken on several sats since before SA was turned off. The new sats have spot beams which can be used to turn off GPS (and may have the ability to introduce random jitter in the outbound signals) in part of the world but the USAF has local GPS jamming that works far better. The problem with turning on SA or blocking GPS in a local area is that having GPS work properly is more useful than having it broken since the US is in a better position to use the technology in a hostile location than the locals are at using it to fight back.

Re:EU Vehicle Tracking Plan (1)

TheTurtlesMoves (1442727) | more than 4 years ago | (#30113388)

SA was a hack on the early systems and the newest sats don't have that ability at all.

Yea Right. And you need a warrant to get a wire tap.

Re:EU Vehicle Tracking Plan (1)

Mr. Freeman (933986) | more than 4 years ago | (#30111464)

There exists the ability for the US to encrypt the signal such that only military receivers can use it. They claim that the newer satellites will be incapable of using this "selective availability". Of course, this is either a complete lie or they already have another system to deny GPS that's called something else that they haven't made public yet.

Re:EU Vehicle Tracking Plan (1)

Beretta Vexe (535187) | more than 4 years ago | (#30109592)

The military reasons are not so clear, both GPS and Galileo are operated by NATO members, they even reached a compromise, that Galileo was to use a different frequency. So you can jam one without degrading your own military signal in the pretty improbable case of a war where both side don't agrees to block they civilian signal.

The first version of the project with a Galileo signal on exactly the same frequency of the GPS to prevent discriminated jamming had a real military interest ( if you jam my signal you jam your too, we both end blind ).

Re:EU Vehicle Tracking Plan (0)

Anonymous Coward | more than 4 years ago | (#30110346)

It's not about "key" roads. It's about *all* roads.

Re:EU Vehicle Tracking Plan (1)

mustafap (452510) | more than 4 years ago | (#30110350)

>Independance from US control is the second motivator.

Primary motivator. Galileo isn't a UK department for transport initiative, you know. In fact the UK, due to it's low funding, is a bit player. ( I'm from the UK and only got to work on Galileo because I was based in another country at the time )

Re:EU Vehicle Tracking Plan (0)

Anonymous Coward | more than 4 years ago | (#30111456)

>>Let's face it. Would you want your military dependant on a system that a culture of well known isolationists who live half a world away can switch off at their whim?

Like European countries, the US was isolationist up to World War 2. But for the years after WW2, calling the US "isolationist" is just some tongue-in-cheek emotional reaction.

Re:EU Vehicle Tracking Plan (0)

Anonymous Coward | more than 4 years ago | (#30113900)

Like European countries, the US was isolationist up to World War 2. But for the years after WW2, calling the US "isolationist" is just some tongue-in-cheek emotional reaction.

Were you asleep during the reign of Bush Jr.?

Road pricing is not "horseshit" (3, Interesting)

Goonie (8651) | more than 4 years ago | (#30112336)

Road pricing is horseshit because if having to drive on a congested road isn't sufficient deterrent to stop you doing it, then taxation isn't going to achieve it.

I agree that mass vehicle tracking raises very serious privacy concerns, but road pricing does reduce traffic. You might be interested in the Transport For London annual report [tfl.gov.uk], which indicates that traffic in the city is about 20% lower than it otherwise would be.

The trouble with your proposal to just track "key" roads is that it encourages traffic to do rat-runs along secondary roads. I experienced this personally when tolling was brought in on a freeway near my house; the alternative routes were suddenly jam-packed with traffic, particularly at off-peak times when they were previously quiet.

Re:Road pricing is not "horseshit" (1)

b0bby (201198) | more than 4 years ago | (#30116262)

The trouble with your proposal to just track "key" roads is that it encourages traffic to do rat-runs along secondary roads. I experienced this personally when tolling was brought in on a freeway near my house; the alternative routes were suddenly jam-packed with traffic, particularly at off-peak times when they were previously quiet.

That's why variable pricing (if implemented sensibly) is a good idea. Off peak, rates should be low or free; peak, prices should rise enough to keep the volume to the point where it's just below congested. People often don't like the idea much, but it's a rational model.

Re:Road pricing is not "horseshit" (1)

RockDoctor (15477) | more than 4 years ago | (#30123550)

The trouble with your proposal to just track "key" roads is that it encourages traffic to do rat-runs along secondary roads. I experienced this personally when tolling was brought in on a freeway near my house; the alternative routes were suddenly jam-packed with traffic, particularly at off-peak times when they were previously quiet.

The house I've lived in for 16-and-a-bit years is within sight of two solutions to this problem : the roads that could be linked up to make a rat run around the local congestion point are blocked off by bollards, so that cars can't drive around them ; more recently, the roads have had "speed humps" added to them which make driving at more than 25km/h an exhaust- and underpan- scraping exercise. Which pretty effectively stops rat-running. From my front door to the "open road" is 11 sets of bumps one way and 13 the other (shorter) way.

Needless to say, when I brought a GPS (well, technically, the wife brought it for my birthday) navigation system for the car, with a year's updates to the mapping of road obstructions and speed cameras, the device insists on directing me down these roads that have been blocked-off for at least 17 years. Which was not a surprise.
So, now you know what level of accuracy to expect from "Road Angel" mapping. We call the squawking voice from the dashboard the "deranged crack addict", on the grounds of it's degree of connection with reality.

Re:EU Vehicle Tracking Plan (0)

Anonymous Coward | more than 4 years ago | (#30113196)

Objective 1.a. is to become independent of whatever guy (or gal) who happens to sit in the Whitehouse then next time we have a crisis where the governments of Europe need to use a GP-system. As a side-effect, Galileo will likely push down pricing and up performance of civilian GPS.

I like it because, as a human being and geek, I want TCAS in my car (and in the cars of all the other idiots on the road) and I may be in the job market for developing TCAS and other satellite- and sensor-based driving aids. Human beings are fundamentally incompetent at repetitious tasks such as driving, so we need systems that help us when we mess up.

Re:EU Vehicle Tracking Plan (1)

jandersen (462034) | more than 4 years ago | (#30113456)

Road pricing is horseshit because if having to drive on a congested road isn't sufficient deterrent to stop you doing it, then taxation isn't going to achieve it

Except that congestion charging in London has been a resounding success. I remember well how it was to drive down Oxford Street before; you could watch your children grow up in the time it took. So that is one place it has worked.

Being able to track the movements of vehicles has many merits, which tend to be forgotten by those who hide behind the freedom- and privacy slogans. And it is not only "the government" being able to spy on your every movement, as if they would want to. Personally I would find it very handy if I could go online to check where my car was if it got stolen. Other potential benefits are:

- being able to put a damper on those people who consistently drive 120 mph on the motorway
- giving drivers an incentive for using alternative modes of transport by charging road tax and insurance by the mile
- crimefighting would be helped a lot if the whereabouts of cars, mobiles and computers were always known

Could it be abused by "an authoritarian regime"? Probably, but then so can everything else. The trick is to avoid having that kind of government; if the population could be bothered to keep themselves informed and take part in the political debate, they have it in their power to do just that.

Re:EU Vehicle Tracking Plan (1)

DNS-and-BIND (461968) | more than 4 years ago | (#30113852)

Well! Any country which uses another country's navigation system for military purposes is just asking for it. It's foolish to the extreme. Seriously, who would ever stake their country's national security on such a thing? Incredibly stupid. Oh yeah, right, it's free and we're lazy.

I don't think anyone has called America isolationist since December 7, 1941. Actually I would welcome some introspective isolationism but then America would get criticized for "turning its back on the world" or something else...it wouldn't even matter, they'd invent something.

Re:EU Vehicle Tracking Plan (1)

AmiMoJo (196126) | more than 4 years ago | (#30113862)

Why bother spending billions on a satellite system when they already record all journeys on traffic cameras combined with numberplate recognition?

general relativity at work (4, Interesting)

bcrowell (177657) | more than 4 years ago | (#30108854)

What I think is really cool about GPS is that without Einstein's theory of general relativity, it wouldn't work. For example, the atomic clocks aboard the satellites run faster because they're higher up in the Earth's gravitational field, and when you're higher in a gravitational field, time flows more quickly. If they didn't compensate for this effect (and a bunch of others), the system wouldn't work at all. Of course you can still find kooks on the internet who think that relativity is all wrong, and have mathematical proofs to that effect. I wonder if those people refrain from using GPS?

Re:general relativity at work (0)

Anonymous Coward | more than 4 years ago | (#30108946)

As I recall, the current system also detects several anomalies that AREN'T explained by Einstein and G R. They can't really explain them, only compensate for them. Who cares, as long as the system works?

Re:general relativity at work (1, Informative)

vlm (69642) | more than 4 years ago | (#30108974)

What I think is really cool about GPS is that without Einstein's theory of general relativity, it wouldn't work.

Oh, it would work just fine alright, in fact it would be a heck of a lot simpler to build and maintain, and probably somewhat cheaper, too. The folks that built the satellites and the base station that sets each satellite clock would have much less headache.

See:

http://www.metaresearch.org/cosmology/gps-relativity.asp [metaresearch.org]

which claims to be a rehash of a chapter of the book "Open Questions in Relativistic Physics"

"Rather than have clocks with such large rate differences, the satellite clocks are reset in rate before launch to compensate for these predicted effects .... Therefore, we observe the clocks running at their offset rates before launch. Then we observe the clocks running after launch and compare their rates with the predictions of relativity, both GR and SR combined. If the predictions are right, we should see the clocks run again at nearly the same rates as ground clocks, despite using an offset definition for the length of one second."

Re:general relativity at work (1)

bcrowell (177657) | more than 4 years ago | (#30109022)

What argument are you trying to make? Are you saying that it would have been easier to build the system without understanding why it behaved the way it did?

Re:general relativity at work (0)

Anonymous Coward | more than 4 years ago | (#30109070)

He might be saying that it would have been easier to build them in a universe where only newton's laws were in effect. ;)

(Different ways to read the phrase "have the laws of x". His interpretation was the one I thought of first, as well.)

Re:general relativity at work (1, Interesting)

vlm (69642) | more than 4 years ago | (#30109152)

What argument are you trying to make? Are you saying that it would have been easier to build the system without understanding why it behaved the way it did?

It would have been easier to build the satellites and ground stations, if GR/SR didn't exist, but individual receiver units don't much care one way or the other. Original post sounded to me like a positioning system can't be made unless it somehow uses GR/SR... Obvious counterexample would be the old LORAN system, which doesn't need GR/SR corrections because the transmitters are stationary instead of orbiting. GR/SR is an annoyance to work around, not an inherent part of location determination.

GPS doesn't calculate position by using GR/SR, it uses time-of-flight to numerous known locations at a known time (downloaded ephemeris, and all the clocks theoretically have the same time). I'm 80 ms from sat 22, 10 ms from sat 15, and 75 ms from sat 19 that means I'm right here (vast simplification) So, GR/SR is not "how it works" or even "needed to work". The onboard clocks don't tick the same rate as ground clocks, so without correcting the satellite clocks, those times of flight would be wrong.

I'm struggling to think of a positioning system design that would require GR/SR to work rather than time of flight... I think it would have to be an active transponder system, or some kind of weird gravity wave detector? It would be interesting.

Re:general relativity at work (5, Funny)

dkf (304284) | more than 4 years ago | (#30109586)

I'm struggling to think of a positioning system design that would require GR/SR to work rather than time of flight... I think it would have to be an active transponder system, or some kind of weird gravity wave detector? It would be interesting.

If we ever need accurate positioning around a black hole, we can at least know that slashdot will be able to tell us how!

And people call us useless! Hah!

Re:general relativity at work (2, Interesting)

thogard (43403) | more than 4 years ago | (#30110090)

The cool bit is that it was known that SR/GR would be an issue before they even launched the 1st sat so there are several ways they can adjust the drift in the clocks both in space and on the ground. It is one reason why GPS is good to less than 10 meters while other space based attempts were good for about a half mile or so.

The observation of GPS clocks and some unexplained issues are why Gravity Probe B was created. Dr. Parkinson was one of the project leaders on both projects.

Re:general relativity at work (1)

MichaelSmith (789609) | more than 4 years ago | (#30110114)

I'm struggling to think of a positioning system design that would require GR/SR to work rather than time of flight... I think it would have to be an active transponder system, or some kind of weird gravity wave detector? It would be interesting.

You could use relativistic effects to calculate the motion of a receiver faster than measuring the movement between two positional fixes.

Re:general relativity at work (1)

bcrowell (177657) | more than 4 years ago | (#30110236)

Original post sounded to me like a positioning system can't be made unless it somehow uses GR/SR... Obvious counterexample would be the old LORAN system, which doesn't need GR/SR corrections because the transmitters are stationary instead of orbiting. GR/SR is an annoyance to work around, not an inherent part of location determination.

Sure, nothing to argue with here. Similarly, Ohm's law is an annoyance to work around if you want electric light, not an inherent part of lighting your house. If you're happy with gas lights, you don't need to know Ohm's law.

GPS doesn't calculate position by using GR/SR, it uses time-of-flight to numerous known locations at a known time (downloaded ephemeris, and all the clocks theoretically have the same time). I'm 80 ms from sat 22, 10 ms from sat 15, and 75 ms from sat 19 that means I'm right here (vast simplification) So, GR/SR is not "how it works" or even "needed to work". The onboard clocks don't tick the same rate as ground clocks, so without correcting the satellite clocks, those times of flight would be wrong.

No, here you're simply confused. You're talking about "known locations" and "known time," and you seem to be assuming that those can be "known" according to Newtonian physics. They can't. The whole point of relativity is that time and space don't work the way you seem to think they do.

Re:general relativity at work (2, Informative)

OldTOP (1118645) | more than 4 years ago | (#30110956)

I think the point is that without knowledge of GR/GS, the satellites would have had clocks set to run at the same rate as clocks on earth, and the system would not have worked until they figured out why the clocks in orbit ran at a different rate, and then figured out how to calculate the proper correction factor.

It took a couple of readings of the post at the top of this thread to figure out what it was trying to say.

Re:general relativity at work (1)

corrie (111769) | more than 4 years ago | (#30111064)

Please explain.

What in Newtonian physics precludes knowing locations or times? Especially considering that both those things are simply definitions, in terms of a locator service.

Re:general relativity at work (1)

Hurricane78 (562437) | more than 4 years ago | (#30111656)

Omg you are so wrong, it's not even funny!

The clocks run FASTER in general, in a higher orbit. Even height variations in the orbit count.

So one *has* to calculate that effect it. No getting around it.
And what I think is usually done, is run the clocks faster by the predictable amount, and then do small corrections for the unpredictable factors.

I don't know where you got the idea that it would only be launching creating an initial offset. But you are really, *really* wrong there. Sorry.

Re:general relativity at work (1)

archont (1215492) | more than 4 years ago | (#30108982)

In regards to your signature, what exactly is an "ayer"?

Re:general relativity at work (0)

Anonymous Coward | more than 4 years ago | (#30109198)

A freakin' big rock in Australia.

Re:general relativity at work (0)

Anonymous Coward | more than 4 years ago | (#30114160)

You can't miss it! It's red!

Re:general relativity at work (1)

Manip (656104) | more than 4 years ago | (#30109060)

I like the subtle derogatory typecasting for "those people on the internet" (who disagree with widely held science). You do realise that if they provide mathematical proofs that they're providing a scientific and intellectual argument and thus should be given the same fair shake as anyone publishing from a Western University.

It is attitudes like this that drive people away from science.

Re:general relativity at work (2)

vlm (69642) | more than 4 years ago | (#30109338)

I like the subtle derogatory typecasting for "those people on the internet" (who disagree with widely held science).

The funny part is the kooks are the ones who "believe" in general relativity... The history of physics is finding new explanations for weird exceptions.

So, 99.999% of the time, especially for pretty much everything earthbound, Newtonian mechanics works great.

Unless you happen to be moving at a fraction of the speed of light, in which case special relativity works great. Well, it works great 99.999% of the time.

SR is great unless you're in a gravity well... Then you need general relativity. Now, the kooks think GR will work 100% of the time, the somewhat more realistic folks think it'll only work 99.999% of the time, we just haven't found that 0.001% yet.

Sooner or later someone will find that condition where GR doesn't work, and get their Nobel prize, after which history will repeat and the kooks will say the new theory is the final 100% answer, not merely 99.999% ...

Re:general relativity at work (1)

Nefarious Wheel (628136) | more than 4 years ago | (#30111224)

The funny part is the kooks are the ones who "believe" in general relativity... The history of physics is finding new explanations for weird exceptions.

Weird? It's fairly simple, and doesn't require "belief" at all. Mass causes space to curve, and curvature causes mass to move. The application you use to effect change is geometry, not prayer.

Re:general relativity at work (1)

drinkypoo (153816) | more than 4 years ago | (#30114586)

Weird? It's fairly simple, and doesn't require "belief" at all. Mass causes space to curve, and curvature causes mass to move. The application you use to effect change is geometry, not prayer.

What is mass? What is space? Do you mean that curvature literally, or is it simply the localized perception of the event? Gee, I guess it's not as simple as you thought it was.

The GP is correct; we cannot know that there will not be special cases where relativity breaks down, just as newtonian physics work just fine until you deal with very small scales or very small or large energy states. To believe otherwise is fairly irrational in my opinion, and unscientific at best.

Re:general relativity at work (1)

syousef (465911) | more than 4 years ago | (#30113086)

What I think is really cool about GPS is that without Einstein's theory of general relativity, it wouldn't work

Neither would the rest of the universe. Well without the physical rules which the model of general relativity approximates. As for the model itself, the universe (including any GPS equipment) ticks along just fine without the theory. The GPS units would just always be wrong (and so not terribly useful)

Re:general relativity at work (0)

Anonymous Coward | more than 4 years ago | (#30117626)

Neither would the rest of the universe.

Of course it would. The universe doesn't care about theories. It just is.

Re:general relativity at work (1)

Undead NDR (1252916) | more than 4 years ago | (#30114410)

What I think is really cool about GPS is that without Einstein's theory of general relativity, it wouldn't work. For example, the atomic clocks aboard the satellites run faster because they're higher up in the Earth's gravitational field, and when you're higher in a gravitational field, time flows more quickly.

Nonsense. And gravity does not have anything to do with that.

The onboard clocks run slower (and thus need to be corrected) because, for the satellites to be in a geostationary orbit at that altitude (IOW, to keep the same angular velocity than Earth), they need a linear velocity that's much faster than Earth's.

Re:general relativity at work (2, Informative)

Agripa (139780) | more than 4 years ago | (#30114750)

The onboard clocks run slower (and thus need to be corrected) because, for the satellites to be in a geostationary orbit at that altitude (IOW, to keep the same angular velocity than Earth), they need a linear velocity that's much faster than Earth's.

The GPS satellites orbit at about 12.5 thousand miles with an orbital period of about 12 hours. They are synchronous with the sidereal day and not geostationary.

The GPS satellite clocks lag by about 7 microseconds per day do to their velocity (special relativity) and lead by about 45 microseconds per day do to their orbital distance from earth's gravity well (general relativity) compared to an earth bound clock.

Let anti-European comments begin in.. (-1, Flamebait)

Anonymous Coward | more than 4 years ago | (#30108960)

3 2 1 ...

Re:Let anti-European comments begin in.. (-1, Offtopic)

Anonymous Coward | more than 4 years ago | (#30111054)

Fucking Eurotrash should hurry up and finish this gay shit so they stop leeching off the US taxpayer funded GPS.

Suck my American cock, you Nazi and Commie faggots!

BTW, you're welcome. :)

Time service (-1, Redundant)

vlm (69642) | more than 4 years ago | (#30109038)

I'd like to buy a NTP appliance that averages together GPS/Navistar, Galileo, and GLONASS for reliability/precision reasons.

I know I can buy GPS based NTP appliances off the shelf for years (decades?), but I'm interested in combined devices.

Obviously Galileo based systems are only vaporware at this time, but someone must have announced something by now?

Re:Time service (0)

Anonymous Coward | more than 4 years ago | (#30109142)

You can buy a receiver for GLONASS. You wouldn't want to average it with GPS, though, because GLONASS is a lot less accurate.

Re:Time service (2, Informative)

juniorkindergarten (662101) | more than 4 years ago | (#30109238)

Actually not so. I had to have a survey done to mark some specific spots for calibrating our gps receivers for dgps. He used a Trimble receiver to mark the spot. The spot was within +/- .1 inch and he verified the accuracy using the Russian GLONASS system. I was quite surprised that he actually did this. He said it was standard company procedure.
There was a point in time where the Russians didn't have the money to maintain the system, however that has changed, and I believe they have been adding sattelites to bring it up to full capacity.

Re:Time service (1)

fenring (1582541) | more than 4 years ago | (#30109374)

Well, that depends on how much money you would put into such a system. For example, Trimble R8 GNSS Receiver [trimble.com] supports all GPS, GLONASS and future Galileo signals. In Europe you could buy such a receiver with ~10000 Euros.

Re:Time service (2, Insightful)

Anonymous Coward | more than 4 years ago | (#30109378)

A gps time source is only off by a handful of ns. You then want to send that time over NTP and add milliseconds of year?

Re:Time service (1)

MichaelSmith (789609) | more than 4 years ago | (#30110218)

A gps time source is only off by a handful of ns. You then want to send that time over NTP and add milliseconds of year?

How else would you distribute your time reference?

Re:Time service (1, Insightful)

Anonymous Coward | more than 4 years ago | (#30109802)

the precision of any of these systems is much higher then NTP; there's no point.

They call it Pathfinder? (0)

Anonymous Coward | more than 4 years ago | (#30110046)

I thought Pathfinder was the project to establish a communications link with Voyager.

Wouldn't it make more sense... (1)

shaitand (626655) | more than 4 years ago | (#30110072)

Seeing as civilian technologies have been demonstrated to get around the artificial limitation in the accuracy of GPS wouldn't it make more sense for the U.S. military to just allow access to the full precision signal to civilians?

Re:Wouldn't it make more sense... (1)

MichaelSmith (789609) | more than 4 years ago | (#30110360)

Seeing as civilian technologies have been demonstrated to get around the artificial limitation in the accuracy of GPS wouldn't it make more sense for the U.S. military to just allow access to the full precision signal to civilians?

They do. In fact the US military is reliant on consumer grade GPS gear so it is unlikely they would ever turn selective availability back on.

The real distinction now is between meter resolution and centimeter resolution.

Re:Wouldn't it make more sense... (1)

shaitand (626655) | more than 4 years ago | (#30112482)

"They do. In fact the US military is reliant on consumer grade GPS gear so it is unlikely they would ever turn selective availability back on.

The real distinction now is between meter resolution and centimeter resolution."

That sounds great but the summary at least says this is about launching sats to use in order to bring resolution down to 1 meter from 10 meter. I believe I had heard that full resolution GPS gave more like 6 inch resolution which is obviously much better than 1 meter.

And neither the summary nor what I had heard meshes with your claim that SA has been turned off and resolutions that are far better than what this new system is supposed to attempt to achieve.

Re:Wouldn't it make more sense... (1)

MichaelSmith (789609) | more than 4 years ago | (#30112858)

And neither the summary nor what I had heard meshes with your claim that SA has been turned off and resolutions that are far better than what this new system is supposed to attempt to achieve.

From the wiki: [wikipedia.org]

GPS includes a (currently disabled) feature called Selective Availability (SA) that adds intentional, time varying errors of up to 100 meters (328 ft) to the publicly available navigation signals. This was intended to deny an enemy the use of civilian GPS receivers for precision weapon guidance.

Re:Wouldn't it make more sense... (2, Interesting)

MosesJones (55544) | more than 4 years ago | (#30111340)

Only if you trust the US to not screw around with it for political reasons. Imagine Sarah Palin as President, who is to say she wouldn't scramble GPS for France & Germany because they refuse to support her invasion of Canada? How about if they release those algorithms and keys just to US companies thus undermining European ones (TomTom etc) and say that the keys can only be exported in completed devices.

The issue with GPS is one of trust and control, simply put the Europeans don't trust the US to play nicely and fair in part because they are funding it.

And if it sounds far fetched... remember the US used to forbid the export of crypto.

Re:Wouldn't it make more sense... (1)

shaitand (626655) | more than 4 years ago | (#30112470)

"Only if you trust the US to not screw around with it for political reasons."

How does a system that improves accuracy of the GPS signal help you if you don't trust the signal in the first place?

Obviously the idea is to improve the accuracy of consumer devices. Who cares about France and Germany? I think the EU is building their own system, let them use that.

Re:Wouldn't it make more sense... (1)

arethuza (737069) | more than 4 years ago | (#30114000)

Surely an easier plan would be to set the RIAA on anyone who "pirates" valuable GPS signals without paying the appropriate fees? :-)

Re:Wouldn't it make more sense... (1)

jp102235 (923963) | more than 4 years ago | (#30114428)

its actually worse than that, the US could arbitrarily, in the event of a national emergency, turn OFF gps. And thus before 9/11, the EU wasn't worried about that scenario, after 9/11, they saw that we could and might turn off the GPS system if/when we needed to. -that could wreak havoc in a lot of places...

J

Re:Wouldn't it make more sense... (1)

drinkypoo (153816) | more than 4 years ago | (#30114700)

"kill switches" in military equipment are SOP and hit the news here recently. on the other hand, trying to paint "the europeans" as one group is as ridiculous as the idea that the EU can accurately represent all its members. You talk about the US government banning export of crypto? Until recently, it was illegal to use almost any cryptography at all in France.

That's not really how SA works (1)

sean.peters (568334) | more than 4 years ago | (#30118506)

Imagine Sarah Palin as President, who is to say she wouldn't scramble GPS for France & Germany because they refuse to support her invasion of Canada?

That's really not how selective availability works. You can't just enable SA for certain people - it's either on (in which case nobody but those with the encryption keys gets it, which would black out high precision GPS for all commercial receivers, world wide), or it's off (in which case everyone gets the unencrypted signal). You can't just punish individual countries.

And it's moot anyway, as many of the satellites currently orbiting, and all the new ones, don't even include the feature. I doubt it's even possible to turn on SA at this point.

Europe's GPS? (1)

Hurricane78 (562437) | more than 4 years ago | (#30111584)

Wow, thanks! And I thought it would be pretty funny, to see a couple of satellites in 17th century clothes, float trough space... )

Re: Europe's GPS? (1)

Hurricane78 (562437) | more than 4 years ago | (#30111612)

Oh, I meant a couple of *bearded* satellites. ^^

Hmm... after looking at the Wikipedia disambiguation page, it could be bearded cars, battleships, aircrafts, or military units too. :)

The more, the better. (1)

Animats (122034) | more than 4 years ago | (#30112754)

This is good. High-precision GPS, which requires seeing 5 or more satellites, is intermittent in urban canyon situations. With the ability to use GPS, GLONASS, and Galileo signals, the odds of having five sats high in your local sky improve substantially. The high-precision (15cm) receivers will be less flakey.

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