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China Begins Using New Global Positioning Satellites 168

Posted by timothy
from the seasonal-ferry-across-the-river-crab dept.
cswilly writes with the news that China's satellite navigation system, called Beidou, has been successfully activated. "With ten satellites now, 16 in 2012, and 35 in 2020, China is making damn sure they are independent of the U.S. military's lock on GPS. According to the article, 'Beidou, or 'Big Dipper,' would cover most parts of the Asia Pacific by next year and then the world by 2020.'" The BBC also has slightly more detailed coverage.
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China Begins Using New Global Positioning Satellites

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  • good (Score:5, Funny)

    by roman_mir (125474) on Tuesday December 27, 2011 @11:58AM (#38503360) Homepage Journal

    the more the merrier.

    • by TubeSteak (669689)

      Accurate to within 10 meters is good?
      Is there any way I can filter that signal out!?

    • by AmiMoJo (196126)

      I don't know why this was tagged funny, diversity is a good thing. Chipsets that support all four GPS systems (EU's, China's, Russia's and the US') are already starting to come down the pipeline.

      And hay, perhaps the US wouldn't lose so many drones to Iran if they didn't rely on just one system to get home...

  • by Ded Bob (67043) on Tuesday December 27, 2011 @12:00PM (#38503382) Homepage

    Or are they GPS satellites "equipped with nuclear missiles and a laser cannon"?

    • by msauve (701917) on Tuesday December 27, 2011 @12:04PM (#38503404)
      You're thinking of sharks.
    • No, but Beidou will help guide their missiles.
      • by jd2112 (1535857)

        No, but Beidou will help guide their missiles.

        And recon drones! If they end up in Iran we'll know where they got their UAV tech from.

        • This was my first thought too now.

          GPS can be spoofed now. It can't be long before wide spread spoofing and jamming takes place. Seems like they'll have to go back to navigating by landmarks. Perhaps they could use something like google earth that scans and recognizes the terrain where they are.

    • by Terrasque (796014) on Tuesday December 27, 2011 @12:40PM (#38503838) Homepage Journal

      Well, a chinese spokesperson was quoted "They are as peaceful as the american GPS satellites, and contain no more armaments than those do" - so no worries.

      We do have some strange reports of a high-ranking american general running from the press conference with a panic-struck look on his face, but that's probably unrelated.

      • by lgw (121541)

        Not really a concern - the US can certainly shoot down all the satellites it wants to. Those in lower orbits like GPS and spy sats can be taken down by (relatively) cheap missiles launched from a jet at high altitude. They'd all be gone in the first few hours of a real war.

        • Not really a concern - the US can certainly shoot down all the satellites it wants to. Those in lower orbits like GPS and spy sats can be taken down by (relatively) cheap missiles launched from a jet at high altitude. They'd all be gone in the first few hours of a real war.

          Our GPS Satellites are in Lower Earth Orbits. These BeiDou satellites are in Geosynchronous orbits, far outside of our missile range, and possibly for exactly this reason. Keep in mind that in that "real war" the process of destroying the few dozens of enemy satellites you want to destroy will produce enormous debris clouds through LEO, possibly destroying yet more satellites and causing yet more debris clouds. This sort of has a MAD effect, as such a shooting war could wipe out most of the planet's LEO rea

          • by lgw (121541)

            Shooting down GEO sats just takes a (much) more expensive rocket (though I suspect there's a MI(n)RV payload for just such a circumstance). I'd guess the plane-carried ABM lasers could fry a satellite in actual Star Wars style as well, if that program happened to be funded by whatever administration was in charge during the war - that's some really impressive technology.

          • by Anonymous Coward

            Our GPS satellites are not in LEO (~20,200 km is the actual altitude).

            https://en.wikipedia.org/wiki/Global_Positioning_System#Space_segment [wikipedia.org]

    • by Lumpy (12016)

      Dont need that.

      Put a small nuclear warhead in the bird and wait for it to be overhead the target. BOOM, a nice wide area EM pulse to take out all of your enemy's electronics.

    • by joggle (594025)

      They are very similar to the European Galileo satellites. They are similar to GPS, but use different frequencies than GPS.

      Originally, China was involved with the development of the Galileo constellation. They backed out because they didn't feel like they had a big enough voice in its development.

      The Chinese constellation, Compass, is intended to be as accurate as GPS. They will almost certainly have their constellation fully deployed long before Europe gets their act together and finishes the Galileo system

  • Old news? (Score:5, Interesting)

    by Bananana (1749762) on Tuesday December 27, 2011 @12:06PM (#38503434)
    we have car navigation systems that use Beidou for some time now (maybe less than a year).
    • by cyfer2000 (548592)
      I will mod this post "informative" if I have points.
    • we have car navigation systems that use Beidou for some time now (maybe less than a year).

      Who is "we"? Are you Chinese?

      • by Lumpy (12016)

        We are the borg.... you will be assimilated.

        • The Chinese Borg use lead-based nanoprobes and the eye lasers have a tendency to blow up.

          Actually, the Chinese do have a lot of parallels with the Borg... steal technology rather than develop it themselves, a large supply of cheap labor, putting the collective ahead of the individual, funny colored skin...

        • We are the borg.... you will be assimilated.

          Resistance is V/I.

  • by tylernt (581794) on Tuesday December 27, 2011 @12:30PM (#38503706)

    From what I can tell from the Wikipedia article, Beidou is an active system where the "client" sends data to the satellites in orbit. It makes perfect sense for the Chinese though, because now they can track where their users are -- something not possible with the passive US system since the receivers only receive and can't transmit any data back. In short, Big Brother Beidou always knows where you are.

    Seems like an active system has a huge disadvantage, though. You can DOS the satellites by pointing an antenna at each satellite and jamming their uplink frequencies, knocking out the whole system for everyone, everywhere. In the US system, you can only jam local terrestrial reception and anybody over the next hill won't be affected.

    • Another implication is that the terminal will be more complex, cost more and consume more power compared with the GPS terminal.

    • by tuxicle (996538)
      So what you're saying is in Soviet Russia, navigation satellite tracks you?
    • by chill (34294) on Tuesday December 27, 2011 @12:49PM (#38503952) Journal

      That was the "test" system. And their description is completely ass-backwards. I'm not sure how useful that would be for mobile units or wide spread use.

      The terminal sends a signal to the satellites (say, 3 seconds latency due to distance). The satellites send the timestamps to a ground station (again, 3 seconds). They do some maths, then send the answers back to the satellites (again, 3 second), which send it back down to the terminals (finally, another 3 seconds). That is like 12 seconds, plus calculations, etc. Good luck using that info reasonably at 100+ KPH

      That still leaves the issue of if terminals become popular, potentially MILLIONS of signals being broadcast skyward for the satellites to receive, sort, stamp and relay.

      The Wikipedia article reads like an instruction manual on how NOT to do GPS. What am I missing?

      • by cswilly (56124)

        Somebody needs to attend his Physics Classes. 3 seconds to send a signal to a low Earth orbit satellite? Non-sense.

        • by chill (34294) on Tuesday December 27, 2011 @01:30PM (#38504422) Journal

          We're both wrong. Me more so than you, however.

          The Beidou-1 satellites are Geo Stationary not LEO. That being said, according to Wikipedia [wikipedia.org] latency is about 1/4 of a second for each leg.

          Still, the idea of transmitting potentially millions of signals blindly in the sky to a constellation of GEO satellites, and letting them do the work of sorting, stamping, and relaying seems a bit ass-backwards.
          Square Peg, meet Mssrs Round Hole and BFH.

        • by youn (1516637)

          To be fair, there may be other constraints such as bandwidth, collisions, processing on both ends... but somehow 3 seconds seems too much for that kind of thing

  • by caseih (160668) on Tuesday December 27, 2011 @12:38PM (#38503806)

    Something I didn't realize until recently is that in the northern latitudes (Canada, northern US), GPS coverage has occasional small gaps in it. My John Deere dealer was saying that in some areas every few days about 6pm (happens to be that time in those areas) GPS coverage drops below 1 meter accuracy levels, and in those areas GPS guidance on farm machines becomes unusable for about an hour or so. As well sometimes a satellite goes offline for maintenance. As agriculture is becoming very reliant on GPS (hence John Deere lobbying in washington against LTE usage of adjacent frequencies), this is a problem. Because of this John Deere now uses GPS and GLONASS together to get better coverage. When Galileo provides coverage, it will use those signals too. The point is, more GPS systems simply improve reliability for everyone, if the Chinese allowed western use of their signals.

    • Re: (Score:3, Interesting)

      When we were traveling across the United States, there was about 45 minutes of our trip through Utah where we were not receiving GPS signals. I believe it happened in the early afternoon. Fortunately there were not turns involved during that portion of the trip.
      • Re: (Score:3, Funny)

        by Anonymous Coward

        That was the Mormon Effect.

      • by Anonymous Coward

        Before GPS we used to use things called 'maps' and something given the fancy-pants name of 'dead reckoning' (figuring out where you are based on direction, average speed, and duration of travel). I am astonished that someone is complaining that they had a 45 minute window (75 km gap at 100 km/hour) where GPS was not available and were worried about getting lost.

        • by GodInHell (258915)

          I am astonished that someone is complaining that they had a 45 minute window (75 km gap at 100 km/hour) where GPS was not available and were worried about getting lost.

          Me too -- where did you read this because it's not in this thread.

          -GiH

    • by DerekLyons (302214) <(moc.liamg) (ta) (retawriaf)> on Tuesday December 27, 2011 @01:44PM (#38504584) Homepage

      Something I didn't realize until recently is that in the northern latitudes (Canada, northern US), GPS coverage has occasional small gaps in it.

      It doesn't. The constellation's orbital pattern is uniform across the entire surface of the Earth.
       

      My John Deere dealer was saying that in some areas every few days about 6pm (happens to be that time in those areas) GPS coverage drops below 1 meter accuracy levels, and in those areas GPS guidance on farm machines becomes unusable for about an hour or so.

      Your John Deere dealer is a little shaky on how GPS operates. The birds are in 12 hour sidereal orbits, which means the pattern (as seen from an fixed location on Earth) repeats every 11 hours and 56 minutes.... Which means (if such an effect as he describes existed) it would steadily and regularly drift earlier through the day. Thus not only would the effect be seen 'about 6PM' every two weeks or so, but it would also be visible at varying times through the day for a week roughly every other week. (This also implies the gaps drift across the Earth's surface in a regular pattern, and would be visible in places other than the northern latitudes.) In addition, he may not realize that GPS accuracy *normally* varies somewhat over spans of a few hours as the geometry of the visible portion of the constellation varies. So what he's seeing is something else, amplified by observer bias.
       

      As well sometimes a satellite goes offline for maintenance.

      Yes, they do. But the system is designed and operated such that having a bird offline for maintenance degrades total system performance by only a very small amount.
       

      As agriculture is becoming very reliant on GPS (hence John Deere lobbying in washington against LTE usage of adjacent frequencies), this is a problem.

      The problem isn't the GPS system. The problem is John Deere is trying to use the system at an accuracy (100% availability at 1m) greater than the specified [civilian] performance levels (95% availability at 7m).

      • by maeka (518272)

        The problem isn't the GPS system. The problem is John Deere is trying to use the system at an accuracy (100% availability at 1m) greater than the specified [civilian] performance levels (95% availability at 7m).

        While I can't speak as to the John Deere system in particular, most the Ag navigation systems are using WAAS on the low end and VRS RTK subscription systems on the high end.

        Here in Ohio ODOT offers a reduced-fee reduced-accuracy VRS option for farmers, who don't need the sub-cm service.

        • While I can't speak as to the John Deere system in particular, most the Ag navigation systems are using WAAS on the low end and VRS RTK subscription systems on the high end.

          WAAS specifications don't meet the 1m/24/7 level either.

          • by ngg (193578)

            WAAS specifications don't meet the 1m/24/7 level either.

            ... which doesn't actually matter because Deer actually uses differential positioning.

            • by maeka (518272)

              To be pedantic WAAS is a differential system.

              And to be overly pedantic for the GP, WAAS specifications don't meet the 1m/24/7 spec, but in practice it is sub meter 95% of the time.

      • by caseih (160668)

        Interesting. I wonder if talking to multiple systems, combined with an accuracy correction, can get the 100% 1 meter accuracy that ag desires. I guess the ag industry's needs is proof that GPS is somewhat inadequate, at least for their needs. Perhaps demand will drive a better overall positioning system.

        • There already exist supplementary systems that can provide that accuracy level. They cost big bucks though.

    • The good news is that it is rather easy these days to build equipment using multiple satellite positioning systems. The Apple 4S for example uses both GPS and Glonass, which is nice as Glonass apparently provides better coverage in western Europe. When Galileo goes live, we'll see circuitry for 3 systems. And at some point it'll be 4 when the Chinese one goes online.
  • by ChronoFish (948067) on Tuesday December 27, 2011 @12:39PM (#38503820) Journal
    Would be possible to get a more accurate position if a receiver combined the various GPS systems - as a kind of check/balance. For non-military use the GPS systems introduce inaccuracies. Is there an algorithm that would bring the resolution down from 10 meters to 1 meter or less?

    -CF
    • For non-military use the GPS systems introduce inaccuracies.

      No, GPS does not deliberately introduce inaccuracy - that was part of selective availability, which was turned off in 1998. What GPS does do is not make available to civilians the correction mechanism that enable military grade accuracy.

      The accuracy of civilian GPS units (within what's available from the system) is mostly dependent on factors outside of the government's control... The design of the antenna, how well it's matched to the re

      • AFAIK cm level accuracy requires differential GPS. Between 1 and 3 meters of the GPS error is due to atmospheric issues. By siting one receiver at a known point, and broadcasting the current 'location' your field instrument can correct it's idea of where you are.

        In essence differential GPS is a local version of WAAS. The closer the receivers are, the better the accuracy.

        Another trick is done by tracking the phase of the carriers. Requires much better electronics, and if you lose carrier sync you have to

    • by batistuta (1794636) on Tuesday December 27, 2011 @02:01PM (#38504786)

      Yes. This has been done for many years in survey equipment. a typical combination of Navstar (U.S. GPS)/GLONASS increases the number of satellites in view and therefore the accuracy. The biggest problem with combinging Navstar and GLONASS is that Navstar is CDMA (code division multiple access) while GLONASS is FDMA (frequency division multiple access). The former technique makes each satellite use a different "language" sort to say, while the later one uses different frequencies. The result is that a dual receiver needs two independent receivers, making them more expensive. New GLONASS satellites will start using CDMA signals in addition to the FDMA, so that legacy receivers work, and some time in the future new CDMA receivers can use both Navstar and GLONASS with a single type of tuner. Galileo was from the ground up designed to use CDMA and as a result, it is much easier to design a Navstar/Galileo dual receiver. As a matter of fact, many survey devices designed for Navstar can be upgraded via a firmware update to use Galileo as well. You can't upgrade to use GLONASS with a simple firmware update, you also need another tuner.
      Regarding accuracy, the thing is that you can't go much less than 5m by just adding more satellites. This is because this error is part of ionosphere delays, and more satellites can't correct this error. It is like trying to do a measurement by averaging 1000 readings, but all done with a bad ruler. At some point, you need to figure out how good your ruler is. And the problem is that this changes dynamically so standard Kalman filter techiques also stop being effective for better than 5m accuracy. There are two approaches for this: the first one is dual frequency, and this is in part how Galileo achieves better accuracy. The idea here is to exploit the dispersion property of the ionosphere. It works like this: different frequencies have different delays, so you send the same signal using different frequencies, measure the delay different, and solve for the ionosphere error. This is what survey-grade equipment do, but they do this by tracking the encrypted military P(Y) code, which is encrypted. The result is a dual frequency solution but full of hacks that make it unstable. This means, as soon as the signal is interrupted for a short time, you need to re-sync.
      The other approach for sub meter accuracy come from differential GPS. This technique uses to close receivers, one with a fixed known location. By measuring the error on the known location, you can apply corrections to the moving rover. But for this you need a link between the two (radio, UMTS, GSM, etc) or some post-processing. In addition, you need receivers capable of recording RAW data and then doing some complex math.
      The cream of the desert comes from using carrier-phase measurements. With this technique you can go up to cm accuracy. This requires tracking the actual carrier wave, and a very precise model of the earth or post-processing software. The accuracy comes at a price: very very unstable. You need clear blue sky and uninterrupted signals. Plus about 20 seconds to lock the signal, even after small interruptions.
      So to answer your question: more satellites guarantee better consistency and readings, particularly in cities and urban landscape. But you can't go below 5m unless you enter differential GPS or dual frequency measurements.

      • by maeka (518272)

        Close.

        Carrier tracking does not require a very precise model of the earth. Real Time Kinnematic GPS has been done for well over a decade with rather sane processing requirements. It also isn't unstable. So long as the L1 and L2 signal of five satellites are tracked one can initialize on the fly, and you only need to track four continuously to maintain said initialization.

        Like differential (a code-base correction) kinnematic requires a base receiver and a rover receiver. They can either be in real time c

  • by Lumpy (12016) on Tuesday December 27, 2011 @12:55PM (#38504046) Homepage

    If the China system does not have the same DOP setup then it will be easy for hackers to use two receivers to read a location from both and create a correctional signal or negate the DOP that the Us military puts on the US GPS system. Giving the TERRORISTS ultra precise coordinates to invoke their TERROR

    Or at least that is how Fox news will spin it.

  • The U.S. has theirs, China just went online, the Russians also have their own and the EU is also planning one. While I can certainly see why each country (or interest) would like to have their own to prevent being locked out - c'mon. What a huge waste of money and resources that could surely be spent in better ways. Then again, militaries have never really been known for their altruistic interests.

    • by DrBuzzo (913503)
      Yes. The US GPS system has never been the only game in town. If they want to add their own, fine, go ahead. I'd love to have more navigational systems that are publicly avaliable so that receivers could be more reliable and acurate. The European system is not going to be fully functional for some time. The Russian Glonas system has global coverage but is not nearly as acurate as the US system in most cases, but they are upgrading it now. They only started coming out consumer-level with combined GP
    • It makes a lot of sense to hit the right spot. No matter the price.

    • by Jeremi (14640)

      The U.S. has theirs, China just went online, the Russians also have their own and the EU is also planning one. [...] What a huge waste of money and resources that could surely be spent in better ways.

      Good point. Maybe the US, China, and the USSR could share a single collection of tanks and jet fighters as well. That would cut out a lot of redundancy, and also save fuel when a war started, since there would be no need to transport weaponry across the globe to fight -- it would all already be colocated together in the same hangar, so they could just start firing at each other right away.

  • by Anonymous Coward

    So they have the technology to position the Earth where ever they please!? Great!

  • From what most people know about China is they make "Excellent Quality" items. How long do you give before we are given a golden shower of chinese satellite parts?
  • I wouldn't trust those clods with printed maps (which are all censored to suit their tastes) so why on earth would I trust them to not only provide me with nav data, but to have the ability to track my receiver? Jeebus....

    All this while the vast majority of their country lives in what most first world countries would consider abject poverty.

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