Comprehensive Manual68
© 2018 Nortek AS
of dirt or small particles.
Deep Water versions (titanium housings) of the Vectors are prone to noise in human environments,
so you may see a higher noise floor than the above listed. This will not be a problem in the field/in
water.
3.1.4 Beam Amplitude and Velocity Checks
The following checks should be carried out in a suitable volume of unobstructed water. We
recommend carrying out initial testing in a test tank, which is both convenient and provides a
controlled environment. If there are insufficient scatters in the water, some seeding material may be
necessary.
3.1.4.1 Amplitude
1) Change the coordinate system to beam Coordinates by choosing BEAM as Coordinate system in
the Deployment Planning menu.
2) Start the test deployment by clicking Online > Start Data Collection or click the corresponding
toolbar button.
3) Click the Amplitude tab (bottom of display) to observe the amplitude of all the beams on the
graphic display.
4) Immerse the instrument so that all the transducers are submerged. Note the amplitude of each
beam, displayed in counts. All the beams should have similar amplitude, within 10 counts of each
other.
As an additional check, each beam can be blocked in turn, by either holding each transducer out of
the water (while keeping the others immersed) or by covering each transducer with a suitable
acoustic attenuating material such as dense plastic, or even a finger. The amplitude of the blocked
beam will fall to around the noise level, while the others will remain unaffected.
When blocking the transmitter, the receivers should report nothing other than noise.
3.1.4.2 Velocity
1) Change the coordinate system to XYZ by selecting XYZ as Coordinate system in the Advanced
Deployment Planning menu.
2) Start the test deployment by clicking Online > Start Data Collection or click the corresponding
menu button.
3) Click the Velocity tab to observe the X, Y and Z velocities on the graphic display.
4) Move the instrument backwards and forwards at a constant velocity through the water, along the
X-axis. A positive and negative deflection of the X-axis velocity should be observed on the graphic
display, while the Y- and Z-axis velocities should remain around 0 m/s. Repeat the procedure for
the Y- and Z-axis. Ensure that the displayed velocities are reasonable.
Read more about coordinate systems in the Principles of Operation, where you will find Beam, XYZ,
and ENU definitions. Note that the X-axis engraved or clarified in form of a colored indicator on the
head/probe of the instrument always points in the direction of beam 1 and a positive X-axis.
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