When being in the Advanced TAB of the configuration tool there is a checkbox called: Enable Low Gain Range. What exactly happens when this box is checked? I have searched the manual, but can't find a definite explanation.
From some comparitive measurements it looks as if the overall gain is reduced by 12 dB. Can someone here confirm this or correct me otherwise, please?
A second question relates to the Frequency Trigger Type under Filtering. When selecting this option I can set the threshold only as a percentage. The other two options (dB and linear value) are not available in this case. They are when using the Amplitude Triggering method. Is this intentional or a bug? If intentional, why are the other two methods not available?
Some clarfication would be much appreciated.
Yes, low gain range was introduced for noisy underwater environments. The full gain of the front-end is shown below:
The details are described here: https://github.com/OpenAcousticDevices/Application-Notes/blob/master/Using_HydroMoth_to_Make_Underwater_Recordings/Using_HydroMoth_to_Make_Underwater_Recordings.pdf
For the frequency trigger, the threshold refers to the frequency response of a Goetzel filter so the 16-bit value isn't really meaningful, and the dB isn't commonly used in this context. In general, setting this value needs some experimentation in AudioMoth Play using pre-existing recordings (https://play.openacousticdevices.info) so adding extra scales seemed to add more potential for confusion.
Full details are in the application note: https://github.com/OpenAcousticDevices/Application-Notes/blob/master/Using_AudioMoth_with_Filtered_and_Triggered_Recordings/Using_AudioMoth_with_Filtering_and_Triggered_Recordings.pdf