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The need of the system has to be announced in cruise planning document "Einsatzplanung" prior to the cruise. The mounting of USBL antenna is executed by ships crew, the operation of the system must be executed by experienced scientific staff. Mounting of antenna takes ca. 45 minutes: removing ice protection of moon pool and lowering GAPS antenna. The reverse procedure for deinstallation takes the same time. In case of sea ice conditions the system must be operated with no ship speed but following ROV or drifting is allowed. In ice free conditions moving of ship is allowed up to 5 knots. Opening angle detecting transponders theoretically amounts to 200 degree. But you need to take the obstruction by means of ships hull into account. In the actual version there is no compatibility to USBL system POSIDONIA (USBL-Box), which is also available on board Polarstern. Online data stream of GAPS is broadcasted via UDP, which can be used by alternative visualization tools (e.g. PosiView) or for seperately loggingPlease note that operations of GAPS requires experienced scientific staff on board. The system is not operated by the ship's crew. Announce operations with GAPS to AWI-Logistics prior to the cruise and clarify the data transfer after the cruise. GAPS underwater communication is conducted by using various frequencies, interferences with simultaneously operating Echo Sounders are possible. Attention: Submarine cable must be connected and device must be submerged in water through moonpool in box keel before activating GAPS. |
Summary
Transducer Frequency:
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GAPS: from 22 to 30 kHz; Transponder: 19.5, 20.0, 20.5 or 21 kHz |
Responsible Persons
Components
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The system consits of the GAPS itself, mounting for installation in the hydrographic shaft, a transponder type MT832E-R, a transponder type MT832E-HD-R with removable head, Easy Connect Box (ECB) and monitoring software "GAPS MMI - Man Machine Interface". The system is hard-wired and the software is installed an configurated. GAPS must be installed in the hydrographic shaft before operating, the transponders can be mounted to winch wire or to a submarine vehicle. GAPS underwater communication is conducted by using various frequencies, interferences with simultaneously operating Echo Sounders are possible.
GAPS:
GAPS is a bi-directional acoustic positioning system, which communicates between ship and one or more transponders. Positions and speed of the transponders can be determined relative to the ship or absolute. GAPS must be installed with custom-built mounting in the hydrographic shaft and is operated below the ship's hull.
Transponders MT832E-R and MT832E-HD-R:
The acoustic transponders must be mechanically attached to underwater objects or vehicles.
The transponders are synchronized to the GAPS and can be operated in transponder-mode (acoustic transmission and receiving) or in responder-mode (electric transmission and acoustic receiving; cables and plugs for responder-mode are *not available on board). Special mounting for operations of the MT832E-R on winch wire is available, e.g. for determination of exact sampling locations in deep water. The transponders can be operated in water depth up to 3000m.
Easy Connect Box (ECB):
ECB is a small interface to connect GAPS, external GPS receiver, PC with MMI-software and data management system DShip. ECB is mounted to the 19" Rack in room A113. The rearward switch activates the ECB, the front switch activates the GAPS.
GAPS MMI - Man Machine Interface - Software:
The MMI-Software starts the GAPS and tracks the underwater transponders. The Software is installed on the CTD-PC in room A113.
External GPS receiver:
On board Polarstern GAPS is connected to the on-board GPS receiver. An external GPS receiver is not necessary on board Polarstern, but it is optional available for other fields of application. |
Position
Data logging, storage and archiving
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The Global Acoustic Positioning System (GAPS) combines an ultra-short baseline (USBL) acoustic positioning system and an inertial navigation system (INS) in the same housing to provide accurate position of any subsea object supplied with a transponder. Operating range is up to 4000m water depth with accuracy 0.2 percent of the distance to the object. The registration angle of 200 degree also enables position detection nearby sea surface. Electronic device ECB (Easy Connection Box) is installed in echo sounder device room E-525a. Operation is performed by software MMI. |
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Transducer Frequency:
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Contacts
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Components
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Position
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Data logging, storage and archiving
Logged parameters
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Central geographical ship's position and time standard
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Time synchronising of the PC with MMI-Software via Windows-Domain-Affiliation. | ||
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Rawdata storage on board
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Data storage in DShip system.
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Dship
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Uncorrected measurement data. | ||
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|| Device name | GAPS ||
|| Parameters | day; depth \[m\]; EW; latitude \[°\]; longitude \[°\]; month; NS; time in hours; transponder no sag; transponder no sax; x coordinate \[m\]; y coordinate \[m\]; year; z coordinare \[m\]; pitch \[deg\]; roll \[deg\]; heading std dev \[deg\]; pitch std dev \[deg\]; roll std dev \[deg\]; altitude std dev; latitude std dev; longitude std dev; heading \[deg\] || |
Data archiving on land
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| After the cruise the DShip data set can be extracted from https://dms.awi.de.
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|| File format(s) | *.txt ||
|| Calibration certificates | NO || |
Documentation
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Documentation
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