February 2020 – TD 266 OPERATING MANUAL – ZPulse® DCS 4420/4830/4520/4930 Page 107
8.3 Tilt Orientation
The distance between each transducer is 90 degrees. Transducer 1 and 3 is on the X-axis and Transducer 2 and 4 are
on the Y-axis.
Transducer 1 is the transducer left and behind when you look at the front of the instrument. The other transducers are
numbered clockwise.
The X, Y and Z-axis are all perpendicular to each other. The positive axes are as a right hand system with positive X-
axis going from transducer 3 to transducer 1, and positive Y-axis going from transducer 2 to transducer 4.
If transducer 1 is aligned to the north, the direction of the beam speed will be zero (in the XY-plane).
A positive heading means that the instrument X-axis is rotated clockwise in relation to magnetic north. When
heading = 0, the instrument X-axis is pointing towards magnetic north.
If the current is along the positive X-axis, you should expect a negative beam speed in transducer 1, and a positive
beam speed in transducer 3. If the current is along the positive Y-axis, there should be a negative beam speed in
transducer 4, and a positive beam speed in transducer 2.
If the instrument is tilted, we define a positive roll angle between the horizontal plane and the instrument Y-axis, and a
positive pitch angle between the instruments X-axis and the horizontal plane.
On the DCS, pitch and roll is defined to be the angle between the instrument axis and the horizontal component of
transducer 1 beam of the transducer head.
Given 4 beam speeds, compass heading and tilting of a current measurement (instrument), the current speeds along
North (N) and East (E) will be calculated. From the N/E speeds absolute speed and direction referenced to magnetic
north will be found.
Figure 8-4: Sensor axis related to heading, pitch and roll
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