> II was wondering that as well. =0D
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Yes the aim is to have a very narrow cone=0D
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>I have experimented with a parabolic reflector for bat detectors. It gave=
directionality but the gain was not =0D
helpful as aiming the rig was difficult because the bats were too mobile t=
o =0D
follow. =0D
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yes it's right I've done a parabolic microphone too with an ultrasonic sens=
or but it's very hard to follow bats while it's easier to listen the bird s=
ong with an audio parabolic microphone=0D
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>There was an increase in gain, but in practice the absorption of ultrasoun=
d in air is the dominant effect on range. The limit for bat detectors with =
Lesser Horseshoe bats is about 5 to 8 metres after which ...=0D
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regarding the amplification it's necessary to use a precision operational =
amplifier, the problem to keep the SNR at a good level. The distance is com=
pletely relative ... to so many factors!=0D
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>The array spacing appears about the same order as the wavelength at 40KHz.=
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it's 7 mm so about 24 khz=0D
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Ivano=0D
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