Research
Tagging
Satellite tags transmit a unique code to polar-orbiting satellites
fitted with ARGOS receivers. This code identifies the tag and the
system uses these transmissions to locate the tag on the earth's
surface. Signals are processed by a ground station in France and
CMAR scientists access the satellite network to see where tagged
animals are.
The ARGOS network was established for researchers and is used
to track may different types of sharks, fish, birds and terrestrial
animals. Satellite tags transmit a radio signal that does not pass
through seawater. The tags are switched off when underwater and
only transmit when the animal comes to the surface and the tag
is above the water. This is why they are located on the
dorsal fin of sharks or other large marine animals.
Detection by a single satellite is sufficient to get a position
for the animal, but the accuracy of the position depends on where
the satellite is at the time and how long the animal is at the
surface. Position estimates are not as good as GPS (which uses
several satellites at the same time to calculate a position). ARGOS
positions are usually within a few kilometres of true and sometimes
as near as 150 metres.
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Last updated
12/11/08
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