Satellite navigation (sat nav) systems are wonderful tools when attempting to determine the proper route to take while traveling in strange lands. When no opportunity to pull off the road and check your atlas or Mapquest directions, a sat nav is there to guide your turns until you reach your destination. Just attach a receiver to your vehicle's visor, dash, or center console and you have a trip advisor that gives you peace of mind. How do sat nav systems work to point travelers in the right direction?
Systems such as the United States' NAVSTAR and Russia's GLONASS achieve their coverage via 20-30 satellites distributed across several orbits. These satellites continually send out signals that carry the time each one was sent, the precise orbital location of the sending satellite, and the approximate orbit of the other satellites in the system. Receivers on or near the ground interpret how long it took for the signal to reach its receptor and calculates the distance to the satellite. It takes the satellite location information sent on the signal and combines it with the distance the signal traveled to identify the receiver's location.
Sat nav systems must perform corrections when calculating positions, however. Satellites send out signals at the speed of light, and if the receiver is only slightly off in calculating the amount of time the signal was in transit, it is multiplied by light speed's rather significant figure and that leads to huge positional errors. Receivers therefore gather information from four separate satellites in order to formulate an accurate reading of their ground position. This position is displayed on a screen, sometimes in motion, so that the user can read the receiver's findings.
Today, a great many sat nav systems operate by applying coordinates received from the satellite signals to maps stored within. The streets, highways, and occasional landmarks stored on these maps are matched up to the satellite coordinates. Users therefore obtain a readout that tells them where to turn instead of latitude and longitude readings that are not nearly as easy to decipher.
Sat nav systems work by combining signals from space with data stored inside a receiver. Those in strange locales are thankful for the help they provide. Travelers have never had such convenience before.
Systems such as the United States' NAVSTAR and Russia's GLONASS achieve their coverage via 20-30 satellites distributed across several orbits. These satellites continually send out signals that carry the time each one was sent, the precise orbital location of the sending satellite, and the approximate orbit of the other satellites in the system. Receivers on or near the ground interpret how long it took for the signal to reach its receptor and calculates the distance to the satellite. It takes the satellite location information sent on the signal and combines it with the distance the signal traveled to identify the receiver's location.
Sat nav systems must perform corrections when calculating positions, however. Satellites send out signals at the speed of light, and if the receiver is only slightly off in calculating the amount of time the signal was in transit, it is multiplied by light speed's rather significant figure and that leads to huge positional errors. Receivers therefore gather information from four separate satellites in order to formulate an accurate reading of their ground position. This position is displayed on a screen, sometimes in motion, so that the user can read the receiver's findings.
Today, a great many sat nav systems operate by applying coordinates received from the satellite signals to maps stored within. The streets, highways, and occasional landmarks stored on these maps are matched up to the satellite coordinates. Users therefore obtain a readout that tells them where to turn instead of latitude and longitude readings that are not nearly as easy to decipher.
Sat nav systems work by combining signals from space with data stored inside a receiver. Those in strange locales are thankful for the help they provide. Travelers have never had such convenience before.
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