Wednesday, July 4, 2012


GPS Signal Errors
Measurement Errors
            Range uncertainty (Due to clock/Atmospheric error)
Errors in position
            Intersection area with error
Errors in GPS Signal
            Orbit error
            Ionospheric error 
            Topospheric error
            Receiver noise
            Multipath
            Jamming
System and Receiver errors
Clock error
Transmission delay
Imprecision in algorithm for range decoding
Multi path errors


Causes of Range Uncertainty

Ionospheric effects                          3 meter
Atmospheric effects                        0.5 meter
Satellite/system errors                      2 meters
Receiver errors                               0.5 meter
Multipath                                         depends
Total Range Error                           6 meters
TOTAL Positional Error                 10 meters


GPS accuracy of GPS depend on
            Dependent errors
                        Noise
                        Multipath
                        Receiver hardware limitation
            Independent errors
                        Satellite clock errors
                        Error in broadcast ephemeris data
                        Signal propagation delay due to Ionosphere and Troposphere


Differential GPS

The differential correction techniques used to enhance the quality of location data gathered GPS receivers.
Differential correction can be applied in
Real-time directly from the field
When postprocessing data in the office

Combining both methods provides flexibility during data collection and improves data integrity

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