Comprehensive Manual92
© 2018 Nortek AS
deployments.
The data from the external sensor will not be affected by the instrument data quality. For example,
the external sensor’s data will be totally unaffected even if the instrument is out of water and thus
measuring noise only.
The input impedance of the analogue inputs is 468 kΩ/100 nF
Example: This example explains how to calculate energy consumption. It covers the energy
consumtion of an OBS3+ sensor, 15 mA, 5-15V supply, that are set up for 30 days deployment.
Duty cycle of OBS: (2048samples/4Hz)/1200sec measurement interval = 43%.
1. Output power voltage set to battery: 11V*15mA*43% = 71mW per sensor. Energy per sensor:
30days*24hours*0.071W = 51 Wh. That is 102 Wh for two OBS sensors.
2. Output power voltage set to 12V: 1.25*12V*15mA*43% = 97 mW per sensor. Energy per sensor:
30days*24hours*0.097W = 70 Wh. That is 140 Wh for two OBS sensors.
3. Output power voltage set to 5V: 1.25*5V*15mA*43% = 40mW per sensor. Energy per sensor:
30days*24hours*0.040W Hi Frans, = 29 Wh. That is 58 Wh for two OBS sensors.
4.2 Analog Outputs
The Vector and Vectrino have the option of outputting data represented as analog signals. They are
able to output the measured velocities on a linear scale, and the voltage output is 0-5 volt. This
voltage must manually be converted to velocities:
0 m/s is reported as 2.5V
-velocity range as 0V
+velocity range as 5V.
Available outputs are 3 velocities (E/X/B1 N/Y/B2 U/Z/B3) and pressure. For standard cable only 3
outputs are available, thus 3 velocities are default.
In both the Vector and the Vectrino, the scaling output for the velocities is chosen in the deployment
planning. It is important to select an analog range that matches the velocity range. You could in
principle use an analog range of +/-7 m/s and a velocity range of +/- 1 m/s, but you would lose a lot
of precision. The best thing is to first decide what maximum velocity that you want to measure and
then select the minimum velocity range and analog output range that includes that velocity.
Note: To use this function Nortek needs to provide a head file with analog outputs enabled. The
correct harness also needs to be installed. Contact Nortek for more information.
Example: The maximum expected vertical velocity is 0.8 m/s, and the the maximum horizontal
velocity is expected to be 2.3 m/s. Configuration:
Select the +/- 2m/s velocity range
Select the +/- 2.5m/s analog range
If the expected maximum horizontal velocity had been 2.9 m/s instead, you could still use the +/-
2m/s velocity range, since the maximum horizontal velocity would then be 3.5 m/s. But you would
then need to use the +/- 7m/s analog output range to be able to represent the velocities from 2.5 m/s
to 2.9 m/s with the analog output voltages. Note that the velocity range is different in the vertical and
horizontal direction whereas the analog output range is the same for all components, beam, XYZ or
ENU.
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