Sonar Transponders

Investigation of sonar transponders for offshore wind energy converters and technical integration to an overall concept.


The operating license of Offshore Wind Energy Converters (OWEC) normally requires the installation and operation of sonar transponder units in order to achieve an acoustical warning of submarines. The exact specification of this kind of warning was worked out by the German navy in cooperation with the Forschungsanstalt der Bundeswehr für Wasserschall und Geophysik (FWG). As underwater sound propagation depends on several influences like seabed properties, sound speed profile and swell, extensive investigations have to be carried out. To this end a cooperation project between the Institut für Statik und Dynamik (ISD), the company THALES Instruments GmbH, the Institut für technische und angewandte Physik GmbH (itap), the UL International GmbH (DEWI) as well as the company BioConsult SH was established.


The installed sonar transponders are intended to be activated by a signal that is transmitted from a submarine in emergency. In this case the transponder is supposed to transmit a recognition signal that allows the submarine a localization of the Wind Energy Converter where the transponder is mounted at. In order to assure a sufficient signal-to-noise ratio and a certain operation distance even under bad conditions the transmission level has to be high enough. On the other hand the impact on marine mammals has to be taken into account both in the far and the near field.

Duration of the project:
03/2009 – 03/2011

Contract number of the project:

Basic questions of this research project

  • Which mounting position beneath the water surface is most suitable for the sonar transponder?
  • How can the sound field be calculated and predicted including the subject to water depth, seabed properties and swell?
  • Which diffraction or interference effects are possible if one or more transponders are activated?
  • How can the influence on marine mammals be minimized?

To obtain an answer to the sketched questions, extensive hydro-acoustic measurements have to be done and computational models have to be developed and validated. The results of these investigations are to be evaluated with respect to their ecological relevance.


  • Institut für Statik und Dynamik (ISD), Uni Hannover, Germany
  • THALES Instruments GmbH, Oldenburg, Germany
  • Institut für technische und angewandte Physik GmbH (itap), Oldenburg, Germany
  • UL International GmbH (DEWI), Wilhelmshaven, Germany
  • BioConsult SH, Husum, Germany

Final report

You can find the final report (only available in German) here.


Fricke, M., Ehrt, O., Hayek, W., Müller-Blenkle, C., Betke, K., Matuschek, R., Gabriel, J., Lübben, A., Erforschung von Sonartranspondern für Offshore-Windparks und technische Integration in ein Gesamtkonzept, Abschlussbericht zum Forschungsvorhaben FKZ0325104A/B, Hannover, 2012.

Oral presentations, Conferences, symposia, workshops

Fricke, M. and Rolfes, R., Erforschung von Sonartranspondern für Offshore-Windparks und technische Integration in ein Gesamtkonzept, Fortschritte der Akustik - DAGA 2012, 38. Deutsche Jahrestagung für Akustik, Darmstadt, 2012.

Fricke, M. and Rolfes, R., Sonar Transponder for sub marine safety: results of the research project at alpha ventus, RAVE International Conference, Bremerhaven, 2012.

Fricke, M. and Rolfes, R., Sonartransponder für Offshore-Windparks, Konferenz des Arbeitskreises Akustik des Deutschen Gesellschaft für Wehrtechnik e.V.: Schall und Schwingungen - Wellen und Turbulenz in sensibler Umgebung, Kiel, 2012.


Fricke, M. and Rolfes, R., Development and Simulation of Sonar Transponders to prevent Submarines from Collisions with Offshore Wind Farm, Poster Session at EWEA Offshore Conference, Amsterdam, 2011.