Vemco HR2, User Manual

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5.2 Deployment Facts and Tips
Before deployment, read these carefully to maximize the performance of your HR2 receivers.
5.2.1 Mooring
HR2 receivers are moored in many configurations often reflecting the bathymetry and
oceanographic/weather conditions. A simple mooring design generally works well. However, in rougher
conditions, heavier weights and mooring lines are usually required.
If a bottom mooring is desired , the HR2 should be positioned above the floor such that it has an
unobstructed “view” of tagged animals within their expected acoustic range. Ensure the HR2’s
hydrophone is
unblocked (do not position an air filled buoy directly above the hydrophone) and free of
any biofouling .
In high flow locations , you may consider using hydro dynamically shaped buoys and low profile
anchors.
For the best horizontal range
, mount the HR2 receiver in a vertical position. Always mount the HR2
with the hydrophone pointing up to the surface, for better acoustic communication with the VR100.
CAUTION: The hydrophone must be kept free of mooring lines and obstructions . Objects around
the hydrophone will adversely affect the detection range of the HR2 receiver.
5.2.2 Spacing
Receiver spacing is generally determined based on range testing and historical acoustic data. Our
position is that you should try to space receivers such that you achieve good detection probability in most
or all weather conditions. It is not always necessary to have 100% coverage if you have several other
locations where you know the animals will be passing through.
However, if you wish to accurately quantify the passing of animals through every receiver location then
you should strive for 100% detection probability. Typical spacing is usually between 100 and 300 meters.
REFERENCE: See the Gate Design tutorial on our website .
Receiver spacing guidelines for VPS studies differ from gate studies because complete overlap of
detection ranges is required for successful fine-scale positioning. For more information on estimating
appropriate receiver spacing for your study, please refer to the
VEMCO Range Test Software
Manual
, from our website, and make sure to conduct tests as described in "Testing the Receiver", on
page 29 .
5.2.3 Biofouling
Some customers use a rubber shrink tape, such as DAFLEX ST250 Cold Shrink Tape, available from
Digikey (W211-ND), to prevent biofouling on the HR2 receiver. It can be used to cover the receiver
body (
do NOT cover the hydrophone
) and does not leave a glue residue when removed. Another option
is to use an antifouling paint, such as Interlux Micron CSC.
NOTE:
Keep the hydrophone uncovered to prevent acoustic dampening.
CAUTION: The Status Light is also a pressure relief valve. Never cover the Status Light/Release
Valve.
The release valve must be able to pop open if needed and must not be blocked by tape or
paint.
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5.2 Deployment Facts and Tips