Hi Juan, What hardware version is this? The vertical bands every 0.33 seconds are the SD card write noise and the wavering line is internal noise in the microphone. This is temperature dependent so will vary a bit over time. The redesign in AudioMoth 1.2 reduced both sources of noise significantly. The noise is often worse as the battery voltage drops, but it's really a trade-off in the design through having all the components (microphone, oscillators and SD card) on the same single-sided PCB. Alex
Hi Juan, What hardware version is this? The vertical bands every 0.33 seconds are the SD card write noise and the wavering line is internal noise in the microphone. This is temperature dependent so will vary a bit over time. The redesign in AudioMoth 1.2 reduced both sources of noise significantly. The noise is often worse as the battery voltage drops, but it's really a trade-off in the design through having all the components (microphone, oscillators and SD card) on the same single-sided PCB. Alex
It goes up and down depending on the day and the hour.