Fixed GPS ambiguity orbit solutions

Flavien Mercier (cnes, France)

CoAuthors

Clément Masson (CS-SI, France); Sabine Houry (CNES, France); Hanane Ait-Lakbir (CS-SI, France); Alexandre Couhert (CNES, France); Eva Jalabert (CNES, France); John Moyard (CNES, France)

Event: 2018 Ocean Surface Topography Science Team Meeting

Session: Precision Orbit Determination

Presentation type: Type Oral

The Jason 3 GPS receiver performs phase measurements with integer cycle ambiguities (unfortunately this was not the case on Jason 2, due to signal to noise ratio issues). This allows to fix the ambiguities in the orbit determination process as it is usually performed for precise positioning on ground receivers.

The method used at CNES relies on zero difference processing, constructing with the phase measurements an equivalent pseudo-range measurement, but with a measurement noise of a few millimeters. To process these fixed ambiguities receiver measurements, it is necessary to use also GPS constellation orbits and clocks computed with the same processing. This is the case with the grg solution (CNES/CLS analysis centre) available at IGS. The feasibilty has been demonstrated on Grace and Jason 1.

The Sentinel 3 GPS receiver performs also phase measurements with the same properties. The tandem phase between Sentinel 3A and Sentinel 3B will give more information on the GPS measurement characteristics, allowing also a direct comparison with the new second frequency signals (L2C) which will be measured on the Sentinel 3B receiver.

These new orbit solutions for Jason 3 and Sentinel 3 show significant improvements in the radial direction which can be validated using SLR measurements. The cross track and along track performances are also improved.

The presentation shows the principle of the operational implementation for Jason 3 and Sentinel 3, and the current performance of the orbits.
 

Oral presentation show times:

Room Start Date End Date
Lagoa Das 7 Cidades Thu, Sep 27 2018,16:30 Thu, Sep 27 2018,16:45
Flavien Mercier
cnes
France
flavien.mercier@cnes.fr