The mounting of USBL antenna is executed by ships crew, the operation of the system must be executed by experienced scientific staff. The need of the system has to be announced in cruise planning docment "Einsatzplanung" prior to the cruise. In case of sea ice conditions the system must be operated with no ship speed but following ROV or drifting is allowed. In free ice conditions moving of ship is allowed up to 5 knots speed using deployable antenna or maximum ship speed using flush antenna or Thomson Marconi antenna. In case of deployable antenna or Thomson Marconi antenna preparation takes ca 45 minutes: removing ice protection of moon pool and lowering antenna. The reverse procedure for deinstallation takes the same time. In case of flush antenna the ice protection window must be opened which takes a few moments. Opening angle for transponder detection amounts to 60 degrees. The detection range amounts to 8000m. Posidonia system is not compatible with USBL system Global Acoustic Positioning System (GAPS), which is also available on board. |
POSIDONIA II is an ultra-short baseline (USBL) acoustic positioning system for tracking of subsea vehicles. |
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On board Polarstern there are three different antennas available, which can be used alternatively but not at the same time. First antenna is flush and permanently mounted in ships keel at ca 11m depth. The antenna is protected by window, which can be opened during operation. Second antenna named deployable antenna is lowered through the moon pool. Third antenna from Thomson Marconi is fixed mounted at a device carrier for moon pool. Active antenna is connected to electronic device named USBL-Box in room E-525a. The control and operation of the system is performed via web-Interface. For Posidonia system are two transponders of type Oceano ET861 and two releasers of type Oceano RT 861 B1S (RT2500 S-Side Bar) on board available. The maximum depth amounts to 6000m. System IXSEA TT801 (SN 002) can alternatively be used to send release commands. Online data stream of Posidonia is broadcasted via UDP, which can be used by alternative visualisation tools (e.g. PosiView) or for seperately logging. |
No local frame definition available. |
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Time synchronising for USBL-Box is provided by TRIMBLE GPS receiver. Geographical ship's position and orientation is provided by MRU Ixblue Hydrins. |
Storage of data in DShip system is established for transponders with number 0 (=antenna), 1, 2, 3 and 4. |
Reduced measurement data. |
|| Device name | POSIDONIA || || Parameters| day; EW; month; NS; position_latitude \[°\]; position_longitude \[°\]; raw_time \[secs\]; transponder_No; transponder No (rel); x \[m\]; y \[m\]; year; z (depth) \[m\] || |
After the cruise the DShip data set can be extracted from https://dship.awi.de/. |
|| File format(s) | *.txt || || Calibration certificates | NO || |