YSI ADV6600 - Manual (Page 177)

Appendix D. Frequently Asked Questions
ADV6600
Y S I Environmental
Page 167
A few examples of good deployment conditions are:
1. Mounting the ADV6600 to a rigid aluminum post or pole that has been sunk into the
bottom of the water body with no ferrous objects nearby. The system will be submerged at
all times.
2. Placing the ADV6600 in a piece of 6-inch PVC pipe that is suspended in the water with a
weight on the bottom of the pipe to minimize movement. Remember that the Doppler
sensor must extend below the bottom of the pipe.
3. Placing the ADV6600 in a piece of 6-inch PVC pipe that is mounted to a rigid post as in
(1) above. Again, remember that the Doppler sensor must extend below the bottom of the
pipe.
For any of the above common deployment methods, the sonde can either be logging to internal
memory using on-board battery power or be logging to an on-site data collection platform (DCP)
that is also supplying power to the ADV6600.
If the sonde rotates during a non-rigid deployment, won’t the direction readings be
meaningless?
Each ADV6600 is equipped with an internal compass that automatically compensates for rotation of
the sonde during deployments. However significant and sharp changes in rotation can cause
temporary inaccuracies in the measurement of the water velocity.
Some points to keep in mind regarding non-fixed deployments:
• The compass is sampled once per second, so rapid rotation of the system can yield inaccurate
compass measurements, and therefore inaccurate velocity measurements.
• Rapid or abrupt movement of the system can cause inaccurate velocity measurements.
• Some slight regular oscillation is acceptable because this movement will be averaged out over
the long term. Keep in mind that a longer averaging interval will help to reduce the effect of
regular oscillations.
• Some rotation of the system will be averaged out over the entire averaging interval, helping to
reduce any “noise” in the measurement.
• The variation in the three rotations (heading, pitch, and roll) is recorded to the system as
Heading Standard Deviation, Pitch Standard Deviation, and Roll Standard Deviation, and can
be used to determine how “active” the movement of the ADV6600 was during the deployment.