3.12 LINEAR DATA ACQUISITION
This data acquisition method allows the data sets to be collected at pre-set pressure intervals, during
the probe immersion. This procedure is commonly used whenever the probe must be used without a
real-time connection with a surface PC; in this case, the probe is pre-set before deployment. Afterwards,
the probe can be deployed for profiling at different sampling sites. Acquisition is performed acting on
the magnetic switch. Once invoked, the following message appears on PC screen.
LINEAR PROFILE DATA ACQUISITION
Acquisition step:0.5
Data collection step expressed in dbar. Please be aware that data will be collected only during
downward profile, or better, only if the pressure increases!
Number of data sets to acquire per each sampling point:2
For each pressure step, it is possible to collect in memory more than one data set contemporaneously.
Do you confirm the above ?:No type [Y]es or [N]o < y
Answer NO return to the data acquisition menu.
Answer YES the probe shutdown waiting the next wakeup to start a data acquisition cycle in function
of pressure
----- UNATTENDED Linear Profiles -------
To start switch-ON the CTD
To stop while switched-ON type <ESC> until confirmation message appears
Now, the operator must switch off the probe by rotating the magnetic switch to OFF position.
Once the probe is operated in unattended mode, the operator is unaware of the probe operations. The
predefined data acquisition cycle end conditions are:
➢ the probe is switched off by means of the magnetic switch;
➢ the probe internal battery is below the minimum operating limit;
➢ the probe data memory is full;
➢ the operator wakeup the probe and interrupt the acquisition cycle
Note
If the probe interfaces a “Rosette” water sampling device, some questions about the water sampling method and
steps are presented to the operator. Details about the water sampling set-up can be found in the Rosette appendix.
3.12.1 Routine operations to perform unattended linear profiles
Once the probe is switched ON by means of the magnetic switch, it watches the pressure sensor waiting
for pressure increments (probe lowering in water). Ending of data acquisition is achieved once the probe
returns to the surface and the operator switch the probe OFF.
Note
❖ The magnetic power ON/OFF switch can start and/or stop an unattended measuring cycle.
❖ Please be aware that, during the unattended linear profiles, the probe does not reduce its power
consumption nor does it switch OFF by itself when back from a profile. To reduce the power
consumption, it must be turned OFF by means of the ON/OFF switch once on the surface.
❖ Please protect the not-in-use bulkhead connectors with the proper dummy connectors.
❖ When carrying out the unattended linear profiles, the probe monitors the battery voltage. In case
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