Satellite And Receiver Clock Errors In Gps

This study utilizes undifferentiated phase data to calculate gps clock errors and to compare with the frequency of cesium clock directly to verify estimated clock errors by the method used in this paper.

Satellite and receiver clock errors in gps.

As it is shown the satellite clocks reach up to more than math 150 math kilometres which leads to huge position errors. Number of satellites visible. To compensate for the discrepancy the frequency standard on board each satellite is given a rate offset prior to launch making it run slightly slower than the desired frequency on. Let the gps receiver receive signals from 4 satellites then there are two cases.

It can be quite large especially if the broadcast clock correction is not used by the receiver to bring the time signal acquired from a satellite s onboard clock in line with gps time. Clock inaccuracies and rounding errors. In a nutshell the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy. The more satellites a gps receiver can see the better the accuracy.

The global positioning system has a clever effective solution to this problem. A receiver s built in clock may have slight timing errors because it is less accurate than the atomic clocks on gps satellites. This eccentricity effect causes the clock rate difference between a gps satellite and a receiver to increase or decrease depending on the altitude of the satellite. To achieve this goal most studies have focused on the relationship between gps receiver clock errors and gps positioning precision.

Gps coordinates calculated when satellites are clustered close together in the sky suffer from dilution of precision dop a factor that multiplies the uncertainty associated with user equivalent range errors uere errors associated with satellite and receiver clocks the atmosphere satellite orbits and the environmental conditions that. Figure 1 illustrates the effect of neglecting the gps satellite clock offsets on the user position. One of the largest errors can be attributed to the satellite clock bias. In addition to the propagation er rors the receiver position accuracy availability reliabil ity and integrity of gps navigation solution are affected.

Introduction gps has been widely used for precise positioning and na vigation applications. Every satellite contains an expensive atomic clock but the receiver itself uses an ordinary quartz clock which it constantly resets. The satellite s reported location may not be accurate.