1 SVY 207: Lecture 12 Modes of GPS Positioning • Aim of this lecture: – To review and compare methods of static positioning, and introduce methods for kinematic positioning. • Overview – Point positioning – Differential positioning – Relative positioning – Static versus kinematic positioning – Precise kinematic positioning
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1 SVY 207: Lecture 12 Modes of GPS Positioning Aim of this lecture: –To review and compare methods of static positioning, and introduce methods for kinematic.
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SVY 207: Lecture 12Modes of GPS Positioning
• Aim of this lecture:– To review and compare methods of static positioning,
and introduce methods for kinematic positioning.
• Overview– Point positioning
– Differential positioning
– Relative positioning
– Static versus kinematic positioning
– Precise kinematic positioning
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Point Positioning• Procedure
– Single receiver, pseudoranges from 4 satellites
– Use satellite ephemerides to compute for each satellite:
» 3 satellite coordinates and 1 clock bias
– Estimate using least squares
» 3 station coordinates and 1 receiver clock bias
• Real-time point positioning– Broadcast Ephemerides from Navigation Message
» Coordinate system: WGS-84
– Typical precision to around 10- 20 metres, NO S/A
– Can average many single point positions to get better position 5 - 7 metres
» For best precision, software should attempt to model ionospheric and tropospheric delay
» Navigation message also contains ionospheric parameters for single-frequency users (few m errors)
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Precise Point Positioning
• Precise point positioning (post-processed)– Precise orbits (IGS, NGS, JPL) and satellite clocks together with