Hi everyone, I'm using AudioMoth dev for bat monitoring in wetlands of southeast México, I'm new to AudioMoth system and I was wondering if you recommend me to use the amplitude threshold trigger or the frequency trigger for recording? For the amplitude threshold trigger I'm using a high pass filter for that Audiomoth save all recordings above 20 kHz (because we have some very low frequency species) and an amplitude threshold of 512 (in the 16 bit scale), but for the frequency trigger I don't understand very well how it works so I'm using the default values suggested in the Audiomoth operational manual. Hope someone can help me :)
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The frequency trigger defines a frequency band, and then a threshold on the response within that frequency band. The best way to explore the settings is to use the AudioMoth Filter Playground - https://playground.openacousticdevices.info. If you have a regular recording of the thing that you want to trigger on, you can load that recording, and experiment with the settings. In the plot below, the red bar shows the frequency band. The shorter the window length, the wider the band. The dark areas of the sonogram are the parts of the bat call that will be recorded in this case.
Using a minimum trigger duration of 1 second will ensure that the whole bat pass is recorded.
The application note here has a lot of additional technical information - https://github.com/OpenAcousticDevices/Application-Notes/blob/master/Using_AudioMoth_with_Filtered_and_Triggered_Recordings/Using_AudioMoth_with_Filtering_and_Triggered_Recordings.pdf