Enabling & Support

Ocean altimetry method and device with improved vertical accuracy

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ESA / Enabling & Support / Space Engineering & Technology
446 - Abstract:
The European Space Agency (ESA) has developed an ocean altimetry interferometric method and device using global navigation satellite signals. This can be used for example in meteorology, maritime navigation and safety industries. The device comprises two antennas and a signal processing system. By using this technology, vertical accuracy measurements (main sea level) can be improved significantly (<10 cm). License agreement collaborations are sought.


The offered technology provides a method for performing Earth altimetry comprising the following steps:

  • Receiving by an upward-looking antenna on a platform above the Earth surface, direct signals having at least two different carrier frequencies transmitted by GNSS satellites in view of the upward-looking antenna;
  • Receiving by a downward-looking antenna onboard said platform signals reflected by the Earth surface and having at least two different carrier frequencies; Comparing carrier phases of said direct signals and received reflected signals, at said carrier frequencies;
  • Determining from said phase comparisons at surface height.


Another object of the offered technology is a device for performing Earth altimetry with an accuracy in the mean level below 10 cm. This device comprises:

  • An upward-looking antenna onboard a platform, for receiving direct signals having at least two carrier frequencies from GNSS satellites in view;
  • A downward-looking antenna onboard a platform for receiving signals at carrier frequencies, these signals being transmitted by each of GNSS satellites and reflected by the Earth surface;
  • A GNSS receiver connected to the upward-looking antenna for providing direct signals having said carrier frequencies;
  • A frequency de-multiplexer connected to the downward-looking antenna for separating the received reflected signals into reflected signals having respectively said carrier frequencies,  means for comparing carrier phases of said direct signals outputted by the GNSS receiver and reflected signals outputted by the frequency de-multiplexer, at said carrier frequencies, and
  • Means for determining a surface height from said phase comparisons.

Innovations and advantages:

The offered technology improves the vertical accuracy of the apparatus in the main sea level to 10 cm.

Domain of application:

This technology could be used in meteorology, maritime navigation and safety industries
Defense communications
Microwave and satellite components (including antennae and amplifiers)
Agriculture, Forestry, Fishing, Animal Husbandry and Related Products