High precision geolocation to 1cm accuracy
Developed by the French government agency CNES, PPP-Wizard technology is a precise point positioning system with a proof of concept on an integer and zero-difference ambiguity resolution method. Adapted from Precision Point Positioning (PPP), a GNSS method able to provide accuracy up to 10cm RMS, this innovation shows higher performance in real-time (up to 1cm RMS) and could find many terrestrial applications.
The PPP-WIZARD demonstrator is a 'proof of concept' of the zero-difference ambiguity resolution method developed in the orbit determination service at the French government agency CNES. Precise Point Positioning (PPP) is a Global Navigation Satellite System (GNSS) positioning method, which provides high-accuracy positioning (10cm RMS). PPP-Wizard, deriving from PPP methods, is able to deliver better performances in real-time (1cm RMS). The demonstrator is built around 3 segments:
- The SSR computation segment, which consists of the computation of orbits and clocks of the GPS and GLONASS satellites, in a state space representation. This is a representation that uses a very low bandwidth for broadcast corrections. This part is by far the most complex one. It uses a global network of real-time GNSS stations.
- The broadcast segment, which consists of the transmission of the orbits and clocks to the users, using a predefined protocol and standard. This segment uses the IGS caster.
- The user segment, called 'PPP Monitoring', based on satellites orbits/clocks corrections coupled with measurements of a receiver, performs precise positioning with integer ambiguity resolution in real-time, as well as the comparison with an absolute reference position, to analyse the quality of the broadcast solutions. For this purpose, the PPP module is limited to stationary receivers.
Innovations & Advantages
- The precision is about one order of magnitude better than the standard PPP methods (1 cm RMS vs 10 cm RMS).
- It does not need a reference station, unlike local methods such as RTK.
- It can be applied globally, with a very low additional required bandwidth, compared to PPP. In particular, this bandwidth is comparable to what is used in SBAS systems or will be used for the Galileo Commercial Service (below 500 bits/sec).
- It is well suited for isolated areas, where no reference station is available.
- It is NOT a regional augmentation method. In particular, it does not estimate atmospheric parameters and does not need a dense network of stations.
Current and Potential Domains of Application
- In precision farming, this solution could enable automatic driving for a wide variety of applications:
- Guidance system for land plot modulation
- Guidance system for targeted use of agricultural chemicals (hoeing, fertilisation, weeding?)
- Guidance system for vine tying
- In the marine area, this solution could enable to reach an accuracy never achieved before:
- Marine mining prospective
- Marine geophysics study
- Oil & gas
- Military applications
- Construction Equipment
- Aeronautics and UAVs: high precision geolocation and navigation