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The GPS Wars Have Begun (techcrunch.com)
Where are you? That's not just a metaphysical question, but increasingly a geopolitical challenge that is putting tech giants like Apple and Alphabet in a tough position. From a report: Countries around the world, including China, Japan, India and the United Kingdom plus the European Union are exploring, testing and deploying satellites to build out their own positioning capabilities. That's a massive change for the United States, which for decades has had a practical monopoly on determining the location of objects through its Global Positioning System (GPS), a military service of the Air Force built during the Cold War that has allowed commercial uses since mid-2000 (for a short history of GPS, check out this article, or for the comprehensive history, here's the book-length treatment).
Owning GPS has a number of advantages, but the first and most important is that global military and commercial users depend on this service of the U.S. government, putting location targeting ultimately at the mercy of the Pentagon. The development of the technology and the deployment of positioning satellites also provides a spillover advantage for the space industry. Today, the only global alternative to that system is Russia's GLONASS, which reached full global coverage a couple of years ago following an aggressive program by Russian president Vladimir Putin to rebuild it after it had degraded following the break-up of the Soviet Union. Now, a number of other countries want to reduce their dependency on the U.S. and get those economic benefits. Perhaps no where is that more obvious than with China, which has made building out a global alternative to GPS a top national priority. Its Beidou navigation system has been slowly building up since 2000, mostly focused on providing service in Asia.
Owning GPS has a number of advantages, but the first and most important is that global military and commercial users depend on this service of the U.S. government, putting location targeting ultimately at the mercy of the Pentagon. The development of the technology and the deployment of positioning satellites also provides a spillover advantage for the space industry. Today, the only global alternative to that system is Russia's GLONASS, which reached full global coverage a couple of years ago following an aggressive program by Russian president Vladimir Putin to rebuild it after it had degraded following the break-up of the Soviet Union. Now, a number of other countries want to reduce their dependency on the U.S. and get those economic benefits. Perhaps no where is that more obvious than with China, which has made building out a global alternative to GPS a top national priority. Its Beidou navigation system has been slowly building up since 2000, mostly focused on providing service in Asia.
Yes, civilian (unencrypted) GPS could be turned off while the encrypted signal remains on. Unlikely, the civilians would be very unhappy. But if a large enough event occurred and the government thought it was a good idea, yes.
The US GPS, Chinese Beidou and Russian GLONASS are all positioning systems intended primarily for military use but which offer a degraded lower-accuracy signal for commercial and private users. The EU's Galileo navigation system offers precision to within a few cms, effectively military-grade accuracy, to paying commercial users as well as open but less-accurate position data similar to the "free" GPS, GLONASS and Beidou systems.
I miss the 'war' part of the article.
Back in the 1990s, the US DoD put out a statement that in the event of a conflict, GPS augmentation systems (which would now include things like the EU's EGNOS) would be considered a valid military target whether on friendly soil or not. It's part of the reason other States started to develop their own systems (except Russia, which was already well established with GLONAS by then).
Quidnam Latine loqui modo coepi?
Thanks for crediting us here in the UK with Galileo, but it's an EU project, not a UK one, and we appear to be shut out of it because of Brexit.
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That is just *so* incorrect! The satellites send precise timing signals, along with two sets of orbital details: the almanack, rough positional information so the receiver knows which satellites to search for if it knows its approximate location and time, and the ephemeris, precise orbital information, for the actual position calculation. It works by measuring the time taken from the satellites to the receiver and triangulating from that (it actually does that in 4 dimensions, needing at least 4 satellites, because the receiver's clock won't be accurate enough to use the timing signals directly to work out the distance from the satellites). When it was introduced, the DoD only made one of the frequencies, L1, available and deliberately degraded it (which was called "selective availability"). That degradation was turned off in May 2000, and further enhancements to the civilian availability have been made such as the introduction of further signals that are easier to detect, make the satellites easier to locate, and compensate better for atmospheric effects.
Quidnam Latine loqui modo coepi?
"Each GPS satellite continuously transmits a radio signal containing the current time and data about its position. Since the speed of radio waves is constant and independent of the satellite speed, the time delay between when the satellite transmits a signal and the receiver receives it is proportional to the distance from the satellite to the receiver. A GPS receiver monitors multiple satellites and solves equations to determine the precise position of the receiver and its deviation from true time. At a minimum, four satellites must be in view of the receiver for it to compute four unknown quantities (three position coordinates and clock deviation from satellite time)."
Selective Availability was a deliberate degradation of the non-military positioning accuracy, "fuzzing" the reported position data. This has been switched off but the most accurate GPS signals are still encrypted and intended only for military and government use, even in the new more accurate GPS satellites being launched.
The Galileo system provides that level of military-grade accuracy (to within a cm or so) to commercial customers, not just the military forces of participating countries and allied forces. It is still encrypted and requires payment and vetting of customers. Galileo's Open Service is accurate to 1 metre, a lot better than GPS' equivalent free service.
It's entirely possible commercial pressures will mean higher-accuracy GPS signals might be made available to civilian users in the future but at the moment only Galileo can provide that sort of service over-the-counter.
Yeah I agree, you WOULD have to be an idiot to say it was Clinton's idea - instead of reading it, where it directly says it was the direct recommendation from the Department of Defense which wrote up the entire thing and proposed it to him.
"Statement by the Press Secretary
RSS Feed White House News
Today, the President __ __ __accepted the _recommendation_ of the Department of Defense__ __ __ to end procurement of Global Positioning System (GPS) satellites that have the capability to intentionally degrade the accuracy of civil signals. This decision reflects the United States strong commitment to users of GPS that this free global utility can be counted on to support peaceful civil activities around the world.
This degradation capability, known as Selective Availability (SA), will no longer be present in GPS III satellites. Although the United States stopped the intentional degradation of GPS satellite signals in May 2000, this new action will result in the removal of SA capabilities, thereby eliminating a source of uncertainty in GPS performance that has been of concern to civil GPS users worldwide."
I suppose if Clinton were Trump (a total retard who didn't listen to expert advice from the Defense Dept generally) you could call it a significant decision to read and sign off on a complete and well-backed DOD proposal / request.
But Clinton, unlike the current idiot, knew he had to take recommendations from experts from time to time, that was part of the job - at that time, YMMV.
All else being equal, if you use N times as many satellites to compute a position/velocity/time solution, your expected accuracy improves by a factor of sqrt(N). But it's not quite that good when you have a multi-solution due to uncertainties in the system clocks between the constellations.
Even in the ideal case, you can usually get more improvement from other techniques than just averaging more inputs. The first thing to attack is ionospheric delays, then a suite of several other errors that are similar in magnitude: GNSS ephemeris (position and velocity) errors, errors in the satellite clocks, other atmospheric delays, etc.
Simple differential approaches use a receiver at a known location to compute (the sums of) several of those errors at each time of interest. Because a single receiver can't distinguish certain errors from each other, those corrections become less accurate over distance. More sophisticated approaches use a widely separated set of receivers to break the errors down into the individual components, so that the corrections can be applied over a wider area.
Uh, what? Yes, the UK does net pay into the EU, as one would expect from one of its richer countries. Germany however, has a net contribution over twice that of the UK (larger as a share of its economy, too). France, too, gives more. This is largely due to the fact that the UK gets two-thirds of its net contribution back as a special rebate. In fact, if you look at net contribution as a share of the national economy, the UK comes in ninth.
Actually the UK is being shut out because _the UK_ demanded that non-EU nations would not have access, back when Galileo was being set up. In other words, it is the UK's own bloody fault for making that demand in the first place.
This is utterly incorrect. We import 3/4 of our food (the official figure is 66%) - which corresponds to 100% in the winder and 50% in the summer. Britain has not been self sufficient in food since the industrial revolution, and prior to then depended on large scale starvation to keep the population down. Our climate and geography make it impossible to grow food for much of the year.
Most of the imported food (by volume) comes from the EU (on account of the Americas and Australia being a long way away).
The main consequence of a no-deal Brexit will be no food in England. However, Boris and Rees-Mogg will be away in their holiday homes abroad, so they don't care. The impact on the rest of the EU will be fairly minimal except in a few industries. (Eg Farming in Spain will suffer a bit).
Disclaimer: I spend 10 years working in food distribution in the UK.
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