Gps - the big idea mathematically
| Added: 13-06-2009 Author: Sara Lee Category: Global Positioning System |
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But we must take appropriate Clocks, how do we measure travel time? Let us use an analogy to explain the explosion silly:
Suppose there are two ways to get a satellite receiver and started playing The Star Spangled Banner in just 12 days. If sound could reach us from outer space (which, of course, is ridiculous) then standing at the receiver we d heard two versions of Star Spangled Banner, one of our receiver and one of the satellite. Both versions will come out of Sync. Derived from the satellite program will be delayed slightly due to travel more than 11.000 miles. If we just want to see how the final version of the satellite, we can delay the initial version of the receiver until he fell Sync is perfect.
Many of us have to move back to the recipient is the same version of the travel for the satellite version. So, we just multiply that times the speed of light and Bingo! we ve got our distance to the satellite. That's basically how GPS. Only the Star Spangled Banner instead of satellites and receivers use something called Pseudo Random Code - which may be easier to sing than the Star Spangled Banner.
Pseudo Random Code (PRC, has been shown above) is part of the basic GPS. S only the most difficult physical digital code, or in other words, it is difficult to fill a series of nuts as shown here:
These signals are so complex that it almost looks like random electrical noise. So the name of Pseudo-Random.
There are several reasons that complexity is good: First, the complex pattern helps make sure that the recipient is not an accident Sync to other signals. The system is so complex that it is possible they will get signal loss, especially as the picture. Because each satellite's unique Pseudo-Random Code this complexity also guarantees that the recipient of an accident won t take another satellite signals. So all the satellites can use the same frequency without Jamming respectively. And make it more difficult to confuse a hostile power system. Even Pseudo Random Code gives DOD to control the system.
GPS was developed by the Department of Defense primarily for military purposes. And even though it was estimated that there are ten times as many civilians as the military system of the recipient is still a significant military. Unique end of the military did not achieve a more accurate P-code pseudo random code. It's ten times the frequency of civil C / A code (and thus more likely accurate) and more difficult to jam. S encrypted when it is called Y-code and only the military and the recipient may receive the encryption key. This is because the two carriers modulated code, advanced games can be played and the frequency to help eliminate errors caused by the atmosphere. But there is another reason the complexity of the Pseudo Random Code, for making important economic s GPS.
Do code may use the information to strengthen the theory of GPS signals. And that is why don t need a satellite dish GPS receiver to receive GPS signals.
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