Please create an account to participate in the Slashdot moderation system

 


Forgot your password?
Close
typodupeerror
×
Space Science Technology

Delta 2 Rocket Launches 50th GPS Satellite 188

Posted by timothy from the more-to-choose-from dept.
wetshoe writes "This CNN article reports that 'the 50th U.S. Global Positioning Satellite has lifted off aboard a Boeing Delta 2 rocket.' It was sent into space to replace an aging GPS satellite. One more reason why geocaching is so much fun."
This discussion has been archived. No new comments can be posted.

Delta 2 Rocket Launches 50th GPS Satellite More

Delta 2 Rocket Launches 50th GPS Satellite

Comments Filter:

  • Geocaching (Score:5, Interesting)

    by rkz ( 667993 ) * on Sunday March 21, 2004 @05:02PM (#8629247) Homepage Journal
    My enjoyment everyday comes in the form of looking forward to the weekend when I spend my free time geocaching [geocaching.com] with my friends or myself.

    Its just you (and maybe some friends), no real pressure. Plus its an actual trek (ranges from in-city, to some caches are ones that need Scuba or moutain gear or whatever).

    And with geocaching you've just got your GPS, a compass, and maybe a topographic map (if you can get one). None of this fancy cell phones with internet to tell you answers stuff ;-)

    • Re:Geocaching (Score:5, Insightful)

      by Anonymous Coward on Sunday March 21, 2004 @05:09PM (#8629279)
      I find it funny that someone carrying a GPS would decry a cell phone user getting answers. How about dropping the GPS and using a compass and topo map ONLY?
      • Yup, and if you need to learn how to use a compass, I'll just plug my pages about it [learn-orienteering.org]. It is a bit dated, I hope to be able to return to it soon.

      • Re:Geocaching (Score:2, Informative)

        by stiggle ( 649614 )
        As someone who helps out with the local Mountain Rescue group - one of the biggest problems they now have is people going out without proper maps and compasses and only their GPS.
        They then phone (cell phone) for rescue cause their GPS batteries are flat and they haven't a clue where they are.

    • Re:Geocaching (Score:2, Interesting)

      by LBArrettAnderson ( 655246 )
      None of this fancy cell phones with internet to tell you answers stuff ;-)

      i wonder what the "treckers" of yesterday would say about your "fancy GPS handheld magellan with programmable direction stuff".

      gotta love geocaching though.... i went once or twice in San Felipe (BC Mexico) and we got to the spot and it matched the description from the webpage exactly, and we looked under the pile of rocks where it told us would be the "prize" and nothing was there. I guess whoever got there before us didn't repl

      • Hmm... where's the "no, it's stupid" option?

  • No info on satellite (Score:5, Interesting)

    by doormat ( 63648 ) on Sunday March 21, 2004 @05:10PM (#8629288) Homepage Journal
    Doesnt say if this is capable of GPS-2 or whatever its called. As someone who uses GPS to manage infrastructure, I'd like to see some more precise GPS without having to spend $20,000 on Trimble [trimble.com] or Leica [leica-geosystems.com] equipment.

  • Kudos to the US (Score:5, Insightful)

    by ergo98 ( 9391 ) on Sunday March 21, 2004 @05:14PM (#8629306) Homepage Journal
    I'm well aware that the EU has plans of a GPS type system, however it does seem a bit unfair that the United States foots the bill for virtually the entire world's navigation system. While the system is primarily there for military means, the US could have encrypted the system from day one to avoid non-military use (which is what many other nations would do), or have offered decryption codes to US organizations to give them a competitive advantage. Instead they've offered it free of charge worldwide, even turning selective availability off so that geocaching adventure is even less of an adventure. Perhaps there's an insidius underlying motive (for example getting the world hooked on GPS while keeping their finger on the conceptual power button), but overall it's a praiseworthy thing they've done.

    • Internet too. (Score:5, Funny)

      by MisanthropicProgram ( 763655 ) on Sunday March 21, 2004 @05:19PM (#8629325)
      We have our moments.

    • Re:Kudos to the US (Score:3, Insightful)

      by gnuman99 ( 746007 )
      Maybe because the US can manipulate it? If a rogue nation's army is trying to get to point A using GPS, the US might direct it to trap B instead :)
      • Is that possible, though? It's my understanding that these sattelites just send out signals saying where they are in space, and it's the GPS device's job to figure out where that puts itself on the ground.
        • Yes its possible.. Just have the satelites lie about were they are...
          Its not easy though and you would impact everyone using gps in a large part of the world.

          Jeroen

        • Re:Kudos to the US (Score:4, Informative)

          by LBArrettAnderson ( 655246 ) on Sunday March 21, 2004 @05:45PM (#8629422)
          all the sattelites do is send out signals of what time it is. they all have atomic clocks on board and just send it out. each device knows where the sattelites are (if i'm not mistaken, either they know or they ALSO send out a signal of where they are, but how are they supposed to know where they are? GPS?) last i heard there were 26 or 27 sattelites operating (50 is how many have ever existed, i'm guessing). So your GPS device also has a clock on it, and it gets a signal from 3 or 4 sattelites (4th for altitude if you want it, or more just for more accuracy) and it compares the time to its own and this way it can know exactly how far away each sattelite is, and it triangulates its position. The clocks work in hundredths of seconds, but the recievers can make these times more accurate by looking at when each hundredth of a second starts and ends blah blah blah. it's a lot more simple than you would think if you just learned about them.

          • Re:Kudos to the US (Score:5, Informative)

            by rijrunner ( 263757 ) on Sunday March 21, 2004 @06:15PM (#8629566)
            There are multiple bits of information buried in the data.

            There is the carrier frequency.

            Then each satellite has a specific identifying signal for each channel called a psuedo random number.

            Then, it layers in a telemetry data packet as part of the actual data transmitted

            http://www.colorado.edu/geography/gcraft/notes/g ps /gps_f.html

          • So your GPS device also has a clock on it, and it gets a signal from 3 or 4 sattelites (4th for altitude if you want it, or more just for more accuracy) and it compares the time to its own and this way it can know exactly how far away each sattelite is, and it triangulates its position.

            Trilateration, not triangulation.

            More info here [cmtinc.com].
        • Yep, as I understand it, it is possible for the US to manipulate GPS signals over a certain region.

          So let's say you're in the middle of a ground war in the, um, let's say Middle East. The (accessible) public signals can be scewed in a fairly localized manner... so that everything in the area appears to be about 1 km to the east, let's say. That's not very handy if you have a rouge nation deploying a weapon that depends on GPS accuracy.

          However, the encrypted military signal can retain it's accuracy... so

    • Re:Kudos to the US (Score:2, Interesting)

      by keith6689 ( 729062 )
      I guess that it costs quite a lot of money to set up and run the system, and that funding would be a lot easier to get if there was some benefit to taxpayers other than indirectly through improved military capability.

      It is good that the US has made the system available effectively without restriction, however now that other nations have realised the value of such a system, it is understandable that they want to be able to operate something similar without whatever political considerations are affecting the
    • the US could have encrypted the system from day one

      it was encrypted from day one. they just recently changed it. (which is good and makes the rest of your post true and insightful)

      • Re:Kudos to the US (Score:4, Informative)

        by RzUpAnmsCwrds ( 262647 ) on Sunday March 21, 2004 @05:55PM (#8629473)
        Not quite:

        The US offered two levels of GPS; one was encrypted and only available to the military; one was unencrypted but had something called "Selective Availability" (SA) turned on which decreased the accuracy by 200-300ft.

        Recently, they have turned off one of the two SA inaccuracies. The military (encrypted) signal is still more accurate (~10 feet), but now the public signal is valid to ~30 feet.

        • Re:Kudos to the US (Score:3, Informative)

          by afidel ( 530433 )
          Actually the military signal is no more accurate in practice except that it offers codes on a second frequency which helps to offset phase shift and multipath. Good commercial unit use the phase information from both the civilian channel AND the military channel (they can encrypt the code but the signal phase is still available) along with the civilian codes. General accuracy of consumer models is limited to around 10m probability sphere which is actually 5m average accuracy. Good equipment using both frequ
        • Afaik, there are ways to improve the GPS signal, Differential GPS [trimble.com] for instance which uses dual receivers. It's reasonably expensive and also has drawbacks, but I wonder why the US military hasn't stopped it by now (didn't they encrypt it for it's accuracy afterall?). Nasa uses [nasa.gov] it too, with an accuracy of 20cm.

          Any ideas?

          • Two reasons why the military hasn't stopped differential GPS:

            (1) In most situations they can't. Differential GPS just broadcasts the difference between a location measurement given by GPS and the actual location of the differential GPS station. So long as you can take GPS readings at a place whith known coodinates, and can make radio broadcasts on the appropriate frequencies, you can do differential GPS.

            (2) Differential GPS base stations must broadcast information. If the military is worried about a

            • Minor correction (Score:3, Interesting)

              by Andy Dodd ( 701 )
              Differential GPS sends corrections for errors in the pseudoranges for each satellite (and in some cases, sends improved ephemerides for predicting the sat's orbit).

              It can be mathematically shown that "Poor man's DGPS", i.e. "This is the lat/long the GPS says I'm at, this is my real lat/long" does not work, and may even degrade accuracy.

              The good news is it's getting easier and easier to create a DGPS source. In the past, it was impossible to get raw pseudorange data from economical receivers. But nowaday

    • Re:Kudos to the US (Score:3, Insightful)

      by grotgrot ( 451123 )
      The US has gone to great lengths to try and stop Europe and Russia from deploying their own systems. They have never explicitly stated the reasons, but most observers come up with defense and control. I'll thank the US the day they stop trying to prevent others from deploying their own systems.

      • Re:Kudos to the US (Score:5, Insightful)

        by pe1rxq ( 141710 ) on Sunday March 21, 2004 @05:45PM (#8629425) Homepage Journal
        Actually Russia already has its own system... (From the cold war era) called glonas.

        Jeroen

        • Re:Kudos to the US (Score:4, Insightful)

          by grotgrot ( 451123 ) on Sunday March 21, 2004 @06:00PM (#8629492)
          Yes (it has two s' - Glonass). My point wasn't that other sources (Europe, Russia) have their own, but that the US has been very proactive in trying to prevent widespread use of them. The aviation press has a lot of information about this.

          I have no issue with the US campaigning to prevent widespread use of the other systems, but I am not going to turn around and thank the US for being so magnanimous when in fact they are advancing their own agenda.

        • Re:Kudos to the US (Score:3, Informative)

          by Ribald ( 140704 )
          Yes, and GLONASS sucks. Maybe even 'sucked'--I'm not sure it's still operational in any useful capacity. As I recall (I'm going from memory here), the GLONASS constellation was optimized for high latitudes--probably a Molniya orbit, or something similar. Anyway, it's more work than just putting them in a half-sync orbit like the NAVSTAR constellation for GPS.

          I know a guy that was with Space Command, working GPS since the early days. He met some Soviet Major (or something) at a conference once, years la
      • Although I've heard of the European Union (EU) trying to come up with their own positioning system, I've never heard anything about the US trying to disrupt this.

        Do you have a reference please, or did you come up with this on your own?

        • Mostly the US has declared that it is 'unnecessary' for the EU to develop their own system or that the planned sytem would disrupt GPS (the planned improvements to GPS due to similar frequencies). Recently the US has come to an agreement with the EU about how the satellites will work. So it does appear that Galileo will become a reality.

          Forbes magazine [forbes.com]

          EU viewpoint [eubusiness.com]

        • As I said in a previous comment, the best reference are the aviation magazines. Sadly few put all the stories online.

          Most places want to move to free airspace, rather than pre-designated corridors. To do so requires better knowledge of where the planes are, and where they are going (this is way more than just TCAS). They also want to improve precision of approaches to runways (where a few meters matters a lot).

          An obvious component of such a system is something like GPS but with greater accuracy. Europ
        • Galileo was shaping up to become a reality around May of 2000. (i.e. the Europeans were getting REAL serious about putting up their own positioning system.)

          Guess when SA was turned off? Guess how fast Galileo turned into a dead project after SA was turned off?

          Nowadays, even if SA is turned back on, it probably won't mean much. DGPS has become far more common than just the USCG stations. (For example, WAAS/EGNOS/whatever the Japanese call their system, all three are identical with different names, whic

    • More like... Shame on US (Score:4, Informative)

      by Anonymous Coward on Sunday March 21, 2004 @06:01PM (#8629496)
      I'm well aware that the EU has plans of a GPS type system, however it does seem a bit unfair that the United States foots the bill for virtually the entire world's navigation system.

      How naive of you.

      US, and specifically those who wrote and otherwise endorsed PNAC [newamericancentury.org] have been doing everything possible to stop the development/deployment of Galileo - GNSS (EU GPS initiative). US isn't providing the rest of the world with global navigation technology out of its heart's content. It's a tool which gives corporate interests as well as military complex a dominant role. There are billions of dollars involved ($12bn and growing), as well as geo-political element of control. Imagine if there was a conflict between China and US in the next decade. Do you honestly believe Pentagon would let the Chinese to utilize GPS in order to strike US targets?

      Paul Wolfowitz was one of those people who was (and still is) opposed to any kind of GPS which isn't under direct jurisdiction of United States. Now that the deal has been reached, it leaves no choice for the hawks to accept the fact that US GPS hegemony will be broken in few years. Competition helps everyone.

      There is also the commercial aspect to it. Galileo, once fully operational by 2007, would suck a huge amount of revenue from GPS. US officials had many reasons to stifle competition in order to ensure GPS monopoly.

      Read the paper on detailing some of the drama and US' sabotage of EU independent GPS system here [216.239.53.104]
      • Thanks for the Google cache link of that paper. Does anyone know where the PDF has been moved? Or does anyone have a copy? I'd like to print it out for reading.
      • Now that the deal has been reached, it leaves no choice for the hawks to accept the fact that US GPS hegemony will be broken in few years. Competition helps everyone.

        How naive of you.

        Did you actually READ the paper you linked to?

        Here's a nice little tidbit for you:
        "Since these bands are so close to the M-code, the signal broadcast on E1 and E2 could potentially interfere with the secure military signal. More importantly, the E1 and E2 bands would be extremely difficult for the U.S. to jam without si
        • The next thing to consider is: WHY would someone want to jam GPS at all? (Ask yourself: What's the major difference between a V-2 rocket and a cruise missle? A highly accurate guidance system.)

          A V-2 is a ballistic missile. Just about all launchers, including the Delta, are ballistic missile derivatives.
          A cruise missile is a missile derived from an aircraft design e.g. the V-1. A Kamikazi plane is a cruise missile where the guidance system is a human pilot.

          It should be possible to jam the civilian US GP
        • This [interestingprojects.com] DIY cruise missle would be a better example to scare people with than the V2.
    • Whilst the US maintains control, they can pay for it. The US has chosen in the past to impact GPS coverage at certain times, there is no reason for other countries to contribute until service is not impacted by political whim.

    • Re:Kudos to the US (Score:3, Insightful)

      by Nimey ( 114278 )
      I hereby declare war on (over)use of the word "kudos".
    • GPS was originally enabled with encryption, frequency hopping, and degraded signals for unauthorized users.

      However, back in the 80's when Russia shot down that civilian airliner that strayed off course, President Reagan made the decision to make GPS publicly available.

      DoD fought off turning off the system all together because we didn't want our enemies to use the system against us. However, with the EU wanting to launch their own and the spreading use of DPGS (differential GPS), it eventually became moo

  • er? (Score:4, Insightful)

    by EMH_Mark3 ( 305983 ) on Sunday March 21, 2004 @05:27PM (#8629359)
    Geocaching is fun because they replace old GPS satellites with new ones? wtf?

    • Re:er? (Score:3, Funny)

      by Anonymous Coward
      Geocaching is fun because they replace old GPS satellites with new ones? wtf?

      I thought that was a strange comment myself, but then considered that perhaps they have no real life or friends. Looking forward to the next satellite replacement might be what gets this person through the day.

      yay! new satellite!

    • there is a simple explanation (Score:5, Funny)

      by QEDog ( 610238 ) on Sunday March 21, 2004 @05:54PM (#8629468)
      Geocaching is fun because they replace old GPS satellites with new ones?

      I think he just hid his cache in the satellite before it went up. Darn, that is going to be hard to get.

  • Geocaching (Score:4, Interesting)

    by Dirtside ( 91468 ) on Sunday March 21, 2004 @05:38PM (#8629396) Journal
    Wouldn't it be more accurate to say that the GPS satellites make geocaching *possible*? Whether or not it's fun has little to do with a rocket launching a satellite. Of course, you could say that it wouldn't be fun at all without a GPS system, since you'd have to navigate with less convenient methods. :)

  • Space Junk, paying the bill, etc, etc (Score:5, Informative)

    by rijrunner ( 263757 ) on Sunday March 21, 2004 @05:40PM (#8629406)

    First.. Space Junk.

    GPS is launched into an orbit some 12,000 miles above the Earth's surface. That orbit has a grand total of about 50 satellites split into 6 different, non-overlapping planes and slightly different altitudes. There are very, very few satellites that go out that far and none have a circular orbit within a few hundred miles of the GPS satellites. Very, very little chance of a collision.

    Also, from that height, the satellites lack enough fuel to deorbit or be sent into the sun. In 1992, my Univ of Colorado aerospace engineering lab went down to the control center and we had a nice tour. I asked the officer giving the brief if they intended to establish some sort of parking orbit for dying satellies as they get phased out. He indicated that it was something they would consider as the constellation gets built out.

    Secondly..

    Paying the bill.

    GPS was encrypted from Day 1. The lower resolution receivers we use just are allowed to decrypt the satellites. It is very difficult to get the higher resolution channel.

    The US government is perfectly willing to let the other countries contribute to the costs associated with running GPS.

    But..

    You might want to consider why the other countries are willing to spend billions on a redundant system rather than pay into GPS or use it for free.

    When someone spend billions rather than use a free service, something is up.

    The US military adamantly refuses to free any of the control of the system up. It is a US *military* asset. As such, it has military utility. They have completely thrown off the commercial channels in the past while engaging in military activities in a region by jiggering with the output to cause the locations to be off. (They can also turn off all the commercial channels on satellites flying over Afghanistan, then turn them back on before the reach the US, for example).

    The rest of the world seems to have some qualms about handing the world's major navigation system to a single provider, for some reason.

    • They have completely thrown off the commercial channels in the past while engaging in military activities in a region by jiggering with the output to cause the locations to be off.

      Although I've heard, and certainly believe, that it's possible for the US to screw up GPS, I've never heard of them actually doing it.

      Do you have some reference for this? I'd be very interested to see more information about these incidents. In particular, I'd like to see what President (I'd assume the decision would be mad

      • During Gulf War 1 they had SA cranked up to the max (~300m error) until they realized that 1) the Iraqi's didn't have any GPS units and 2) there were not enough military GPS units available for all the troops. So they completely turned off SA and handed out quickly requisitioned civilian GPS units to the troops.
    • Maybe they should rename it MS-GPS, because then suddenly most people won't mind the single provider issue, and better yet they wouldn't mind any reliability problems... They could even make it much more expensive and require all GPS receivers to regularly 'call home' to check for "software updates", and people still won't mind.

  • Some math (Score:4, Interesting)

    by steveha ( 103154 ) on Sunday March 21, 2004 @05:41PM (#8629410) Homepage
    The article says the satellite costs $45 million. I Googled a bit and found that the launch cost for a Delta 2 is around $50 to $60 million. The article also said the satellite being replaced is 11 years old, and at the end of its useful life, and that there are 50 GPS satellites.

    Crunching the numbers, we have about $105 million to put up a GPS satellite, with about 11 useful years; call it $10 million per year. Multiplying by 50 satellites, we have $500 million per year cost for GPS. I never knew. Also, on average, each year 4 or 5 launches must happen to replace aging GPS satellites.

    Note that the launch costs are actually higher than the cost of the satellite. Also, the satellite could probably be made more cheaply if launch costs were lower (instead of over-engineering it to never break, they might just launch a cluster of two in the same orbit, or just design it to be easily repaired). If and when private companies build reusable spacecraft that can carry a GPS satellite, the cost of GPS will go down a lot. A Boeing Delta 2 is completely used up in each GPS launch right now, so truly reusable spacecraft should be able to dramatically cut launch costs and still make money.

    steveha

    • Re:Some math (Score:5, Insightful)

      by Y2K is bogus ( 7647 ) on Sunday March 21, 2004 @05:55PM (#8629472)
      Umm, you aren't counting right.

      That's the 50th satellite launched. That means $105m * 50 over the entire life of the GPS project.

      IIRC, there are only 26 operating satellites, give or take.

      Honestly though, do you believe the gov pays $105m for each satellite in orbit? There are plenty of ways for them to get their money back.
      • IIRC, there are only 26 operating satellites, give or take.

        I Googled and found that there are currently 28 [navy.mil]. Thanks for the correction!

        That means $105m * 50 over the entire life of the GPS project.

        We shouldn't assume we can multiply 50 by $105 million, because the earlier GPS satellites were different and probably cost more. And I don't have any data at all on R&D costs, which you could add to the price tag. I was just interested in the costs of keeping the current system going, and how many lau

        • Re:Some math (Score:3, Interesting)

          by thedillybar ( 677116 )
          I don't understand this comment. "Get their money back"?

          It goes something like this.

          1) Pay Lockheed & Boeing to get the bird in the sky.
          2) Tax Lockheed & Boeing.
          3) Tax the income of the employees of Lockheed & Boeing.
          4) Tax this money again when they buy stuff (sales tax).
          etc. etc. etc.

          If I had to guess, the only money the US is actually losing (dollars leaving the country) on this project is for the fuel and maybe some titanium (or other raw materials). AFAIK, both Boeing and Lockhe

          • Sure, the government collects a lot in taxes. But I don't think you can really figure that in to the price tag of a project like this. You could mention taxes anytime you talk about the government spending money.

            steveha
    • I don't think there's such thing as an easy repair on a sattelite. Manned spaceflight is way more expensive then sending up another sattelite.
      • Manned spaceflight is way more expensive then sending up another sattelite.

        It is now. True reusable spacecraft will change the game very much.

        Currently, you build your space objects as large single pieces, with maximum size depending on which rocket you will use to do the launch. In the future, you will build your space objects as modules that dock together, with module size chosen to be convenient for the cargo capacity of your true reusable spacecraft. It will be much cheaper to send up several laun
    • "If and when private companies build reusable spacecraft that can carry a GPS satellite, the cost of GPS will go down a lot."

      Given the cost of a shuttle launch in comparison with Atlas and Delta launches, I haven't seen the proof yet of a cost savings by using a reusable launch vehicle.

      By the way, it's the space elevator and space tethers that bets are being taken on for cheap launches these days.

      • Good grief! The Shuttle is a horrible boondoggle. It is reusable in name only. It takes months of full-time work by a standing army of hundreds of people to refurbish a shuttle to make it ready to fly again.

        We need the space equivalent of a 747 airplane: something that spends more time flying than being refurbished. That will bring down launch costs a great deal.

        A space elevator would be great, but I don't want to wait for one. That's much harder engineering than a truly reusable spacecraft. And you
        • What I was trying to say that I havent seen one of those 'truly reusable spacecraft' yet, and maybe the shuttle taught us that it is not possible to make such a thing that actually saves money. Technical details such as limits on materials and temperatures and other stresses may make it impossible to make the '747 equivalent' reusable space vehicle.
          • maybe the shuttle taught us that it is not possible to make such a thing

            What the Shuttle taught us is that it is not possible for NASA to make such a thing.

            No one has done it yet, but it actually looks reasonable. It's not clear that we can build a single-stage-to-orbit (SSTO) reusable spacecraft with our current knowledge, but it's quite clear that we could build at least a two-stage design (TSTO) where both stages are truly reusable. And most of the experts think SSTO is doable. It won't have much c

  • To Clear up some things.... (Score:5, Informative)

    by spankus ( 140336 ) on Sunday March 21, 2004 @07:59PM (#8630189)
    1. GPS satellites have never "degraded" service over an area. Anyone who says so, doesn't have the right data, or has been smoking the ganja a little bit too much. To anyone who doubts this...How bad do you think the PR would be if GPS was unable to be used for airline navigation, or search and rescue, or worse than that caused some crash?

    2. The satellite launched was a Block IIR vehicle. Block IIR-M and IIF vehicles are still in a very low orbit (close to sea level..haven't been launched.)

    3. We can't burn satellites in from semi-synchronous orbit (the GPS orbit) using today's technology. When they're disposed of we kick them away from the earth a couple of hundred kilometers. Orbital degradation is slight at semi-synchronous, but the satellites will interfere with each other in about 6,000 years. I hope we'll be able to clean it up before then.

    4. GPS Signals arrive on two frequencies, L1 (L1 = 1575.42 MHz) and L2 (L2 = 1227.6 MHz). C/A code (which is FREE as in air to civil users) is modulated onto the L1 carrier signal. It has never been encrypted. It has been degraded (selective availability, the method of degradation, was turned off in 2000) but is now every bit as accurate as the military signal. The only significant advantage the military receivers have is the ability to correct for ionospheric defraction using both frequencies.

    5. The major driver behind Galileo (EU GPS) is economics. Basically the US has a handle on a 12 billion dollar industry and the EU wants its share. They're expecting to charge money for the same service the US gives out for free! Somebody failed economics.

    Feel free to respond with any questions, I'd love to answer them.

Slashdot Top Deals

"One day I woke up and discovered that I was in love with tripe." -- Tom Anderson

Close