Introduction to Satellite Tracking GPS Technology

09.20.2010

positioning system, the horizontal accuracy of approximately 30 meters, SPS and subject to selective benefits (Selective Availability, SA) process, that is, will the location of the satellite signal or time data re-processing, before joining the random changes in parameter error will increase, so its accuracy is not higher than the SA of the error. SA-SPS accuracy level value of 100 meters, 156 meters vertical, time 340 seconds to 10 parts per billion, is now available for general business applications such as car navigation systems.
PPS system is using encrypted signals, the level of positioning accuracy is 20 meters, 27.7 meters vertically and time is 10 parts per billion to 200 seconds. As PPS to pin code system, it will not be added to SA code interference, in fact, PPS is also only available to military units and government use, to ensure military security, the U.S. Department of Defense will join SA in the general civilian GPS jamming a little garbled to ensure the stability of the government and military secrets.

Error control
GPS is a passive (Passive) system, a user receiver can only receive signals coming from one direction. From the satellite to the receiver between the satellite launch is to rely on measurements of radio signals to the receivers of the time, multiplied by the speed of light from the distance, the location of the receiver to calculate the three-dimensional coordinate values, the prerequisite is to know from the satellite ephemeris data to calculate the orbit of each satellite location, so that each can correct GPS receiver position.
Measurement of the GPS time must be two different tables, so will have an asynchronous transmission time deviation, usually a very small error can cause a great error on the implementation. Now people use the accuracy of GPS receiver receives only about 95% accuracy within about 100 meters, for the elimination of error, the GPS technology now known location by latitude and longitude coordinates, the error

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