GNSS RTK network for the Grand Port Maritime de Bordeaux

Publié le 28 October 2016
The mission & the problem

At the end of January 2011, Cadden delivered to the Grand Port Maritime de Bordeaux (GPMB) a network of nine GNSS receivers in RTK mode via UHF link.

Composed of three dual-frequency stations and six mobiles from the Ashtech Proflex 500 range, this new device is intended to offer the bathymetry teams of the Grand Port Maritime de Bordeaux precise positioning throughout the approximately 150 km of the estuary of the Gironde, between the Port and the Atlantic.

Récepteurs GNSS en mode RTK via liaison UHF pour la vedtte hydrographique Astrolabe du Grand Port Maritime de Bordeaux

Three technical strengths enabled specialist Cadden to win the call for tenders last June:

  • The performance of the UHF radio link was at the forefront of the criteria of the Grand Port Maritime de Bordeaux within the framework of this important equipment project: with three reference stations, the network put in place makes it possible to fully cover the vast river area.
  • The “Hot stand-by RTK” mode (formerly “Back-up” mode) ensures reception of the RTK differential correction signal without any interruption when the mobile receivers, on board the boats, pass from one reference station to another .
Time for change

This proven functionality, unique to Ashtech receivers, remains unique in the market. Its principle: calculate the same position twice and simultaneously, but from two different reference stations. In the event of signal disturbance, switching from one measurement to another is immediate and transparent to the user, with the same level of precision. In addition, the centimeter Z of the RTK system will allow the Grand Port Maritime de Bordeaux to directly use “GPS tide” data.

Vedette hydrographique Astrolabe du Grand Port Maritime de Bordeaux

Finally, thanks to the integrated web server, the system offers the possibility of controlling the reference stations remotely via IP from a simple PC: a “plus” that will prove to be very useful, even if it does not. was decisive in the final choice.

As soon as it goes into operation this month of March 2011, the new GNSS network will enable bathymetry work to be carried out with greater precision. It will thus serve two priority objectives of the Grand Port Maritime de Bordeaux: the quality and safety of maritime access.

This order complements the June 2010 order for four dual-frequency single-beam sounders, one of which was integrated by Cadden in a waterproof case.

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