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Please 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.

GAPS: from 22 to 30 kHz; Transponder: 19.5, 20.0, 20.5 or 21 kHz

The system consits of the GAPS itself, mounting for installation in box keel, 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 through moonpool in box keel 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 through moonpool in box keel 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.

Time synchronising of the PC with MMI-Software via Windows-Domain-Affiliation.

Centering of GPS-antenna position to GAPS and to transponders.

Data storage in DShip system.

Uncorrected measurement data.

|| 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 \[deg\] ||

After the cruise the DShip data set can be extracted from https://dms.awi.de.

|| File format(s) | *.txt || 
|| Calibration certificates | NO ||