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Reject Wind/Rain Noise

The Amplitude level threshold corresponds to the Level threshold of the Trigger Event and determines the sensitivity of the broad-band noise detector. For proper operation, this threshold should be lower than the Level threshold for the Trigger Event.

The Wiener Entropy threshold is applied to the instantaneous spectra once the Amplitude level threshold is exceeded. If the entropy of the current signal exceeds this threshold, the signal is internally labeled as a potential noise signal. The state of this intermediate signal is averaged by the specified Averaging time constant, which provides a measure of the instantaneous duty cycle of the noise signal. If this measure exceeds the Duty cycle threshold, the trigger will be deactivated for the specified Hold time. These settings can be tested for instance by using a previously recorded .wav file (Device = "WAV file") that contains the undesired noise signal. During monitoring, a lower case w indicates that the trigger is currently inhibited due to the wind/rain noise rejection mechanism.

The entropy and its threshold can be visualized by activating the option "energy in f-range" on the Display list box. The green dots then represent the instantaneous values of the entropy and the horizontal solid green line is the threshold that can be modified by mouse dragging.
Avisoft Bioacoustics

last modified on 03 December 2018