July 2019 – TD 304 OPERATING MANUAL – Doppler Current Profiler Sensor
Page 55
2.4.11
Output enabling – Sensor Parameters
In this section sensor
parameters related to the
compass/tilt measurement are
enabled or disabled.
Alternatively setting are either
Off
or
Output
.
Figure 2-32: Definition of output sensor parameters
A compass/tilt measurement is taken for each ping measurement (current speed measurement).One ping consists of
one ping from each transducer. The given value is an average of all single measurements from the last measurement
interval.
The Heading is the angle in degrees between transducer 1 and magnetic north. Turning the sensor clockwise gives an
increasing angle. When looking at the sensor from the label side, transducer 1 is the transducer back to the left (refer to
). When looking at the sensor from the label side with the sensor upside down, transducer 1 is the transducer
back to the right.
The tilt is converted to rotational angles, Pitch and Roll. The rotational angles are used internally when calculating
correct heading from the 3D magnetic field vector and correct current speed components from the acoustic beam
vectors in each cell. The Pitch and Roll output is an average from all measurements in the last measurement interval.
The Heading Output
is the average compass reading referenced to north during one measurement interval.
Pitch Roll Outputs
individually outputs
Pitch
and
Roll
as an average for one measurement interval.
Abs Tilt Output
(Absolute tilt) is the tilt between the horizontal plane and the sensor’s plane. When upside down, the
Abs tilt is varying around 180 degree. This is different from the Aanderaa RDCP (previous profiler generation). The new
profiler is able to sense if it is upside down or not, and the absolute tilt indicates the actual direction of the sensor when
it is running.
Max Tilt Output
(Maximum tilt is the highest abs tilt in any direction measured by the sensor during one measurement
interval.
Tilt Direction Output
is the average of all tilt direction measurement during one measurement interval.
Std Dev Heading Output
(Standard Deviation Heading Output). The sensor does one heading measurement for each
ping. This is the standard deviation of all the heading measurements during a recording interval.
Std Dev Tilt Output
(Standard Deviation Tilt Output). The sensor does one tilt measurement for each ping. This is the
standard deviation of all the absolute tilt measurements during a recording interval.
