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16 - GNSS and applications

16 - GNSS and applications

16.1 - Global Navigation Satellite Systems (GNSS)

16.1.5 - Concluding remarks

Improvements in GNSS applications by upgrades of and additions to the available GNSS signals:

  • The higher pseudorange accuracy of the new signals
  • The availability of many more satellites at once
  • Both the availability of more radio frequencies and satellites

Challenge for multi-GNSS positioning
Inter-System Biases (ISB):

  • Different GNSS may have an offset in time with respect to each other due to maintenance.
  • These biases must be studied, and if possible corrected or eliminated.

16.2 - Application

  • GPS: smartphones, car navigation, and personal navigation
  • PPP: lane-specific navigation advice for road users
  • RTK: surveying for creating maps and construction works
  • Carrier phase-based positioning: Deformation monitoring (Earthquakes, volcanic activity, mining or extraction of petroleum or natural gas…)
  • SBAS: Aircraft precision approach and landing
  • RTKGNSS: machine guidance, in particular, self-driving vehicles

Exercises and worked examples

Q: The largest remaining error sources in short-baseline DGPS?
The atmosphere delays, the satellite orbit and clock errors.

Q: Which positioning modes have decimeter positioning accuracy, how long for the measurements?
RTK provides decimeter or even centimetre accuracy, within 100 sec of measurements.
DGPS can reach decimeter accuracy, but considerable time to allow for averaging(1h).