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The VHF signal is obscured because:
• Of rain, snow or fog
• The animal is on the move through
wet vegetation
• The animal entered a gully, crossed
over a ridge or moved behind a large
rock outcrop
Use your local knowledge of the terrain
and your knowledge of the animal’s
behaviour to predict where the animal
might be.
Stand on the deck or roof of a truck to
cover a greater range.
Try to obtain a direct line of site, or
climb to an elevated location, e.g. hill
top or use triangulation.
There is too much noise around to hear
the VHF signal.
Use headphones with your VHF
receiver.
Lightweight headphones may be
adequate. If tracking in high noise
areas, e.g. near aircraft or waterfalls, use
fully enclosed quality headphones.
Danger: When wearing headphones,
stay alert for approaching predators.
Problem
The direction of the VHF signal is hard to determine.
Possible Scenario
Solution
The VHF signal is bouncing off the local
terrain, e.g. mountain walls, rock out-
crops or a tree
The transmitter may be pointing in the
direction from which it received the
signal, e.g. the mountain wall, rock
outcrop or tree.
Climb to the nearest ridge to pick up a
clearer signal or take several readings
from different positions and use
triangulation to pin point the location
of the animal.
You may be getting closer to the VHF
transmitter.
Reduce the VHF’s receiver’s sensitivity
until it is just audible.
The transmitter’s signal is coming from
all directions. This is known as
swamping and means that you are very
close to the VHF transmitter.
Detach the antenna from the VHF
receiver, and increase the VHF
receiver’s sensitivity (gain). Some
receivers also come with an attenuator
that you can use.
