Has anyone else experienced bad audio on all recordings? I'm hearing a loud repetitive sound no matter the gain nor sample rate. It is a constant repetitive thud/static/propeller/synthesizer modulation sound. Audio is being recorded, but the electronic synth sound drowns out quite a bit of it.
I'm assuming either a bad part or a mistake in the soldering? Does anyone have suggestions on how to fix it?
I have included an audio sample below...
Thank you very much for this information, I will change the batteries before using them again this month. Is there anything I can do to avoid the noise due to the temperature?
Sampling rate 384kHz, and the card is SanDisk Extreme 32GB (not extreme pro) the audio moth devices are in a forest (inside a ziplock), an yes, it ocurres in some recordings. Also, sometimes this noise appears too at 86kHz:
There is also some small background noise from the SD card writes but this seems to be more pronounced. What sampling rate are you using? Is this an Extreme or Extreme Pro SD card? Is the AudioMoth in a housing? Does is always occur or just on some recordings?
Hi, I am having the same problem with the "clicking" noise at 18-20kHz. If I slow down the rate to 0.2 it sounds like a clock. I have 4 AudioMoth devices, all with Energizer AA batteries and sand disk extreme of 32gb. The noise appears in a few recordings regardless the device (it appears in all of them but we don't know what's activating it). However, when analyzing the spectrogram it becomes an issue because it overlaps with the sounds we are interested in.
I would try a different SD card first if you can - I don't think we've ever tried a Sandisk Ultra card. Also using batteries is also safer as it isn't clear how noisy the USB power supply will to be under varying load - some might work better than others. All our recordings are on Sandisk Extreme and either regular Alkaline AA or Energizer L91 AA (http://data.energizer.com/pdfs/l91.pdf) batteries.
Can you do a test recording inside with the device about 50cm away and just count out loud at normal speaking volume, with the device recording at 48kHz and gain level 2. Preferably use standard Alkaline AA batteries for this. The recording should be nearly noise free with very clear audio. If you email me the recording (alex.rogers@cs.ox.ac.uk) I can check it.