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. 11 meter depth. The antenna is protected by window against ice sheets. The window can be opened during operation, but during open window and ice covered situation the ship must not be driven.
Second antenna is a deployable antenna by means of lowering through the moon pool.
Third antenna from Thomson Marconi is fixed mounted on a device carrier to be lowered through moon pool.
Active antenna is connected to electronic device named USBL-Box. The control and operation of the system is performed via web-Interface. Typically the system is operated from laptop on the bridge by laboratory electronic engineer.
Online data stream of Posidonia is broadcasted via UDP, which can be used by alternative visualisation tools (e.g. PosiView) or for seperately logging.
Mobile system IXSEA Oceano TT801 can alternatively be used to send release commands.
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 operation depth of these devices is 6000 meter. | 
