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| bat
detectors |
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It
is a myth that bats are blind – they have
eyes and can see in dim light. However, in darker
conditions they use echolocation – sounds
which are reflected back by objects. Bats detect
these echoes with very sensitive ears and can
avoid obstacles, navigate, locate their position
and chase insects. The frequency of the call
is generally too high for the human ear, so
a bat detector is needed – an electronic
instrument that processes the bat call so we
can all hear it.
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There
are three types of detector, heterodyne,
frequency division
and time expansion. |
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| Heterodyne |
This
is by far the most common detector and
is a good one to start with if you intend
bat detecting. Heterodyne detectors
have good tonal qualities which help
in identification of different bat species. |
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Frequency
Division |
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detector processes the incoming sound
from the bat by dividing the signal by
10. For example, 5OkHz becomes 5kHz. However,
there are no tonal qualities to help with
identification. |
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Time
Expansion |
The
signal is captured and stored digitally
and then replayed at a slower speed.
This reduces the frequency of the sound
to audible levels. It is ideal for research
using computer analysis and sonograms.
Time expansion models are generally
very expensive. The
disadvantage of this detector is that
it goes ‘deaf’ while it
is playing back. |
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Heterodyne
detector |
costs
around £140 |
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Frequency
Division |
costs
aound £275 |
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Time
expansion |
costs
aound £1,100 |
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For
more information on bat detectors,
just drop us a line at: |
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bat
detectors |
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As
a voluntary organisation we |
exist
entirely on donations |
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