Have you ever wondered how your sat nav receiver uses satellite signals to calculate your precise location on the Earth's surface? Here's a non-technical explanation to satisfy your curiosity. The first factor you need to know is that your receiver has to obtain a signal from at least four satellites as a way to calculate your location. You'll find presently about 30 GPS satellites orbiting the Earth, and at the very least 8 are in a direct line of sight having a given point on the Earth's surface at all times. So so long as you're not deep underground, satellite reception is rarely a issue for receivers.
The only thing your sat nav receiver knows about a single GPS satellite is its distance from you. It determines this by sending a signal to the satellite and receiving a response. Due to the fact radio signals often travel at the speed of light, the delay in response allows the receiver to calculate how far away the satellite is. But with only a single satellite, your receiver has no way of determining what direction the signal is coming from. In the event you envision a sphere centred on the GPS satellite, as well as the radius of the sphere will be the distance between it and your receiver, your location could be anywhere on the surface of the sphere.
This is why multiple satellites are required. Say your GPS receiver repeats this method having a second satellite. You now have two spheres, but because your location is on the surface of both spheres, you'll be able to now narrow it down to somewhere along the intersection of these two spheres. The intersection of two spheres is really a circle. But you could still be situated anywhere around the circle. So add a third satellite as well as a third sphere. A circle intersects a sphere at only two points, so you now know that your location is 1 of those two points. At this point, your sat nav device could just assume that you are at the point that's truly on the Earth's surface and be carried out.
The dilemma with employing only three satellites is that the clock inside your sat nav receiver is not one hundred percent accurate. Becoming off by even a tiny fraction of a second can throw off the calculations, considering that such significant numbers are involved. This is why the signal from a fourth GPS satellite is needed.
If your receiver's clock had been ideal, the fourth satellite's calculated sphere would intersect one of the two points mentioned above. But because your clock is not best, it is going to be off slightly. In this case, all your receiver has to do is measure the distance between this point and the surface of the fourth sphere. It then uses this distance to correct for any clock inaccuracies. And that's how the Global Positioning System locates you.
The only thing your sat nav receiver knows about a single GPS satellite is its distance from you. It determines this by sending a signal to the satellite and receiving a response. Due to the fact radio signals often travel at the speed of light, the delay in response allows the receiver to calculate how far away the satellite is. But with only a single satellite, your receiver has no way of determining what direction the signal is coming from. In the event you envision a sphere centred on the GPS satellite, as well as the radius of the sphere will be the distance between it and your receiver, your location could be anywhere on the surface of the sphere.
This is why multiple satellites are required. Say your GPS receiver repeats this method having a second satellite. You now have two spheres, but because your location is on the surface of both spheres, you'll be able to now narrow it down to somewhere along the intersection of these two spheres. The intersection of two spheres is really a circle. But you could still be situated anywhere around the circle. So add a third satellite as well as a third sphere. A circle intersects a sphere at only two points, so you now know that your location is 1 of those two points. At this point, your sat nav device could just assume that you are at the point that's truly on the Earth's surface and be carried out.
The dilemma with employing only three satellites is that the clock inside your sat nav receiver is not one hundred percent accurate. Becoming off by even a tiny fraction of a second can throw off the calculations, considering that such significant numbers are involved. This is why the signal from a fourth GPS satellite is needed.
If your receiver's clock had been ideal, the fourth satellite's calculated sphere would intersect one of the two points mentioned above. But because your clock is not best, it is going to be off slightly. In this case, all your receiver has to do is measure the distance between this point and the surface of the fourth sphere. It then uses this distance to correct for any clock inaccuracies. And that's how the Global Positioning System locates you.
About the Author:
Abe Ford is an expert in Quality Sat Nav Voice and related topics. To learn more, visit http://www.satvoices.com today!
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