32
Rev. C • 10.2004
Power Level
The power level bar sets how much acoustic energy the instrument transmits into
the water. Select between HIGH and LOW (for both versions). The difference
between the highest level and the lowest level is about 7dB.
Coordinate System
The coordinate system can be selected to Beam or XYZ. Beam means that the
recorded velocity will be in the coordinate system of the acoustic beams, about
15 degrees with respect to the vertical. XYZ means that the measurements are
transformed to a fi xed orthogonal XYZ coordinate system.
Speed of sound
Speed of sound can be set by the user (Fixed) or calculated by the instrument
based on the measured temperature and a user-input value for salinity (Meas-
ured). The salinity is 0 for fresh water and typically 35 for the ocean.
Output Sync
The SyncOut signal consists of 1.95 ms long, 3.3V pulses that can be confi gured
for two different schemes of output synchronization.
If
Output sync for other sensor is selected, the SyncOut pulse will be output in
the middle of each velocity sampling interval.
If
Output sync for Vectrino is used the SyncOut pulse will be output at the com-
pletion of each sampling interval. In addition one SyncOut pulse will be output
when the sampling of velocities is started.
Input Sync
The SyncIn signal permits external control of the sampling. Two options are
available; initiation of the Vectrino sampling upon receipt of an input pulse, or
full external control of the data collection rate. Typically, another instrument
will provide TTL pulses required to trigger the data collection or the signal can
be used as a remote switch that allows the operator to start data collection at the
push of a button.
Select Start on sync to have the Vectrino start data collection on the rising edge
of the SyncIn signal. Sampling of velocities then proceeds at the set sampling
rate. After data collection is started the SyncIn is ignored. The fi rst velocity
sample is completed one sample interval (1/Samplingrate) after SyncIn becomes
‘high’.
CHAPTER 5
Setting Up for Operation
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