ecoObs GSM-BATCORDER 1.0, User Manual

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11.3.2019 GSM BC englische Version 1.0 working copy - Google Docs
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OPERATION MANUAL GSM-BATCORDER 28
TSL value
The sensitivity of the GSM batcorders microphone may be reduced if it is used over
a longer time ‘in the field’. Properly installed it is relatively robust, but long-time
uninterrupted outdoor use let it age early. Especially humidity and frost tend to be
negative on the microphones lifespan. Because the conditions on wind energy
plants are especially extreme, the sensitivity might decrease significantly after one
year of use. Because the collected data might then not be comparable any more, a
recalibration or change of the microphone will be necessary.
The sensitivity of the microphone is determined by the built-in ultrasonic transmitter
of the microphone. At the beginning and the end of each SCANNING session a test
signal in form of a short sine wave is played and compared with the reference value.
The result of this comparison is displayed as the ‘TSL value’ in the status SMS.
Measuring the sensitivity in this way can never be as reliable as measuring the
sensitivity in a special sound laboratory. Many environmental factors such as heavy
humidity or a raindrop covering the membrane of the microphone can lead to very
low TSL values even though the hardware is completely all right. If on the other hand
an obvious decline (value -6dB) of the measured TSL value is observed over a
couple of days, a significant loss of sensitivity can be assumed.
A decline of -6dB hereby corresponds to a signal loss of 50%. Fluctuations of 0dB
to -6 dB are a result of the weather conditions and no reason to worry.
TSL reference value
The TSL reference value is used as a reference for the test signal at the beginning
and the end of the SCANNING session.
Is is advised to set the reference value once the GM batcorder is installed and the
microphone disc is installed in its final position. The measurement of the reference
value can be repeated any time.
You will be asked to set the TSL reference value every time the TIMER is activated
(see above). When you have decided to activate the timer you are asked to set the
TSL reference value. By pressing the ‘right arrow’ button (
▸
) test signal is played
and the value is set. By pressing the ‘left arrow’ button (
◂
) you skip the reference
measurement.