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July 2019 – TD 304 OPERATING MANUAL – Doppler Current Profiler Sensor
Enable Burst
Mode. The sensor can run in burst mode or spread mode. When burst mode is enabled the sensor
performs all ping measurements at the beginning or end of the recording interval, dependent on the Burst Period
Placement setting. This can be set to either
are evenly spread out during the recording interval. The instrument activates sleep mode between each measurement,
which reduces the power consumption. Power consumption in spread and burst mode is about the same. Refer
3-30.
Figure 3-31: Spread mode and burst mode ping distribution during the recording interval
3.6.4
Surface
Figure 3-32: Surface
Enable Surface Cell
will set a cell in the surface layer. The data is set as not valid if the sensor is placed upside down
with the surface cell enabled.
the impedance difference between the water and air creates an almost perfect reflector, and the acoustic signal is
reflected by the surface. Regardless of the cell size used to process the surface cell, this cell will be dominated by the
infinitesimal thin layer between water and air. Although the surface cell is infinitesimal small, the cell size used to
process the data must be sufficiently large to capture the boundary between air/water defining the surface cell.
The surface cell will reflect the speed of the "boundary condition". Wind will generate capillary waves, and rapidly
accelerate the surface boundary. For this reason there will be a strong correlation between wind speed/surface
boundary speed and wind direction / surface boundary direction.
NB! Do not use Surface Cell or Surface Reference together with Upside Down enabled, refer chapter 3.6.1.
The surface reference is ignored if the sensor is upside down while it is running (columns forced to be sensor referred).
Upside Down
If instrument is oriented
Start Of Interval
Surface Cell Size
or the measurement "window" is centred on the surface. At the surface,
the surface cell is ignored and the data is set as non-valid.
or
End Of
Interval. If it is disabled the ping measurements
Spread Mode
Burst Mode – End Of Interval
Burst Mode – Start Of Interval
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Figure
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