| ENVISAT - GPS Buoys
The photograph
is featuring the type of buoy used within this calibration project. It is
the so-called "Große Fasstonne" (big cask tun, abbr. FTB) with a diameter
of 2 metres and a length of 3 metres. The sea light can be seen in the middle
of the Fasstonne. The weight of the buoy is around 2300 kilograms. The system
is stabilised by a massive steel chain (Hahnepot) of 350 kilograms which
is connected to both eyelets at the ends of the buoy and attached to the
fibre rope at its middle leading to a V-shape of chain under water.
 An
additional platform was installed carrying the sensors and their energy supply
as well as the solar panels on the very top. Additionally, a visual sign
(yellow cross, 2 metres long) is mounted on the buoy's head with the tilt
sensor and the GPS antenna installed at its end and, finally, a 2 metres
long telemetry antenna on the very top. The pressure sensor measuring the
dip-in-depth of the buoy is placed on the outside and can be seen at the
interface between the hulk parts painted in yellow (above sea level) and
brown (below sea level), respectively.
The system
is moored by the Hahnepot steel chain attached to the buoy and connected
to a light-weight fibre rope. An anchor stone of concrete with a mass of
3000 kilograms completes the mooring system (again with a conventional steel
chain as connector).
You may
also have a look at video clips of the buoys
in the harbour of Alcudia/Mallorca and of the
FTB test deployment.
Reference Station
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