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USER MANUAL / MANUEL UTILISATEUR
Figure 2: Schematic representation of a PROVBIO-B's depth-cycling during the Mission.
(1) Delay Before Mission
To prevent PROVBIO-B from trying to sink before it is in the water, the float waits for this time before
starting its descent. This happens only before the first cycle; it is not repeated at each cycle.
(2) Transmission / Reception / GPS location
Before each cycle, the PROVBIO-B float stays at sea surface and transmits the data collected during
the previous descent - drift - ascent cycle.
The IRIDIUM satellites system receives these data. Thanks to a GPS receiver, an accurate position of
the float can be obtained and the clock of the float be updated at UTC/GMT time. If commands are sent
by mail to the IRIDIUM system, they are dowloaded and processed at this time.
Before the first cycle, only the technical message including the GPS position of launching is transmitted
by the float. This enables to check if the float is operational before starting the mission.
Note: if a tri-profile option is selected, one Iridium transmission only will be sent at the end of the 3
profile for the 3 profiles.
(3) Descent
The float descends at an average speed of 5 cm/sec. During descent, which typically lasts a few hours,
PROVBIO-B can detect possible grounding on a high portion of the seabed and can move away from
such places (see section
measurements during descent. Optical measurements acquisition are not carried out during descent.
In order to respect the requirement of the ARGO program, the first cycle of the mission collect CTD
measurements during the descent at the sampling period of 10 seconds.
(4) Drifting at Depth
During the drift period, PROVBIO-B drifts underwater at a user-selected drift depth, typically between
200 and 1,000 meters below the sea surface. The drift period is user-selectable and can last from 1 day
to 6 months, but is typically 10 days. The float automatically adjusts its buoyancy if it drifts from the
selected depth by more than 5 bars over a 60-minute period. PROVBIO-B can only collect CTD
measurements at user-selected intervals during this drift period if the user selects this option.
PROVBIO-B
3.3. page 7
for more on grounding). PROVBIO-B can collect only CTD
PAGE : 6 / 72
DATE : 26/03/2008
INDEX : A
REF. : DOC08018
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