"Pathfinders" Take Shape For Galileo, Europe's GPS 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."
Funding (Score:2, Interesting)
general relativity at work (Score:5, Interesting)
Re:Funding (Score:2, Interesting)
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:general relativity at work (Score:2, Interesting)
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 (Score:3, Interesting)
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:EU Vehicle Tracking Plan (Score:5, Interesting)
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:Wouldn't it make more sense... (Score:3, Interesting)
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.
Road pricing is not "horseshit" (Score:4, Interesting)
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.