Chinese GPS System To Be Offered Free 131
MattSparkes writes, "The Chinese GPS system, Beidou, is apparently to be opened up for free access within China, worrying European investors on the €2.5 billion competing project, Galileo. Initially, China had declared that access to their system would be restricted to the military, and Europe had planned to recoup some of the cost of their system by selling licenses to China. Michael Shaw, from the US government's National Space-based Positioning, Navigation and Timing Coordination Office in Washington DC, said, 'Frankly, China's behavior towards Europe is not so different to how Europe behaved with us when GPS was the only game in town a decade ago.'"
Re:China (Incompetent, Offtopic, Flamebait, Troll) (Score:2, Informative)
CC.
Re:How many do we need? (Score:3, Informative)
U.S. already has the new GPS IIF nearly ready for launch. And GPS III is in its early stages of life. The technology does not stand still.
Re:Chinese giving away nothing (Score:2, Informative)
The Europeans have the advantage of learning from the mistakes made by the Air Force, as well as newer technology. GALILEO is a win-win for users, because it is causing the acceleration of the GPS program, GPS-III should be operational years ahead of schedule (and many augmentations originally slated for block III are now in IIF - launch starts 2007). When combined GALILEO/GPS recievers are released to market, the accuracy commonly available to civilians will increase because of the added frequencies and potentially better geometry. Another potential benefit could be a dramatically reduced barrier to entry in the GPS/GNSS reciever manufacturing and design industry. The current players are working hard now to keep their dominance when the new systems are operational.
As for the Chinese, I don't think they will 'struggle' all that much, but I guess time will tell. The fact that they will have a free to use segment just means that the system will actually be used by the public, instead of primarily the military.
Re:More precise? (Score:3, Informative)
See my posts above, but essentially... yes, it is possible to get a better position. The methods are different from what you have described however. If the same receiver can receive signals from all of the systems, there are more satellites available giving you the potential for better geometry. Another big factor is the addition of a third frequency, which carries another civilian-accessible code, this signal will allow the effect of the ionosphere to be removed from the range measurements, meaning that your position accuracy will increase.
Receivers that can use both GPS and GLONASS signals already exist, but they do not treat the two systems as separate, they use all the available information from both together to generate the best possible solution. The catch? Price. A receiver capable of GPS and GLONASS measurements will undoubtedly also be capable of carrier-phase measurements and receiving both L1 and L2. This type of receiver will have a geodetic type antenna (not the kind you can carry in your pocket), and probably cost on the order of $10,000-$30,000. These are widely used in land surveying, you are unlikely to find someone who owns one without using it to make a living.
For info on these high-end receivers, see http://trimble.com/ [trimble.com], http://leica.com/ [leica.com], http://novatel.com/ [novatel.com], or http://professional.magellangps.com/en/ [magellangps.com]
Re:More precise? (Score:1, Informative)
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Well, your reasoning is generally correct, but that is not exactly the way it would work. When you get into the details, reality tends to get more complicated. Those circles you are talking about as a representation of the accuracy, really refer to a percentage of time your accuracy will be within the given circle. Sometimes you will be outside the circle, so it is not necessarily true that if you have 3 signals, you will be inside the overlapping areas of those circles. For example, even if you have a "3 meter accurate" signal, you will probably be 6 meters off occasionally. If they all had the same level of accuracy, you would probably get a better solution by averaging the three inputs, but in reality, each system probably has significantly different accuracy. If one signal was 2 meter accuracy, and the other was 20 meter accuracy, you would just degrade your solution if you simply averaged them (for two signals). So you would want to weight things toward the more accurate systems. Now, that is doable. If you had a ground station, over time, you could accurately characterize the accuracy of each system, and then develop an optimum algorithm to weigh them according to their accuracies. - Vector J
Re:but their compass points south! (Score:3, Informative)