Good afternoon
We have a number of AudioMoth 1.2.0 with firmware version 1.8.0 or 1.8.1. and we use them to record bats.
Until recently they worked fine, but gradually they started producing thousands of nonsense tiny files (39-61 kb) and only a handful of good ones scattered here and there, even in areas with many bats. In some cases they produce only the tiny ones, and no big/good files at all. The settings are the same as before (see end of message for an example).
Yesterday I tried one device with settings in the audible range and it worked well (on my desk). Then I used the usual settings for ultrasounds and put it outside overnight - today I found out that the problem was still there.
We are trying with new alkaline batteries like Energizer and sd cards suggested by Open Acoustics
Any ideas how to solve it?
Thanks in advance
Sample rate (Hz) : 384000
Gain : Medium
Sleep duration (s) : 1
Recording duration (s) : 5
Active recording periods : 2
Recording period 1 : 00:00 - 03:30 (UTC)
Recording period 2 : 14:30 - 24:00 (UTC)
Earliest recording time : ---------- --:--:--
Latest recording time : ---------- --:--:--
Filter : Band-pass (11.0kHz - 144.0kHz)
Trigger type : Amplitude
Threshold setting : -32 dB
Minimum trigger duration (s) : 0
Enable LED : Yes
Enable low-voltage cut-off : Yes
Always require acoustic chime : No
Use daily folder for WAV files : No
Disable 48Hz DC blocking filter : No
Enable energy saver mode : No
Enable low gain range : No
Hi, It seems to have written a correct T.WAV file. If I expand the file using the tool in the Config App I get the full 5 second file that is expected.
The sleep period and the recording period are both quite short so the AudioMoth will typically struggle to keep to the schedule once there are many files on the SD card. We'd normally use a 55 second (595 second) record period and a 5 second sleep period to minimise the amount of time that is lost opening and closing files. I don't think the above factor is the issue here however. The example file contains no trigger events within the 5 second recording period. This may be because there were no audible bats within the interval, or it may be a microphone problem. With the setting you have, you should be able to rub your hands together in front of the microphone to trigger longer recordings. You will see the red LED flashing as it is writing the file to the SD card. If you record at the default 48 kHz, without a case, and count in a normal voice about 40 cm from the AudioMoth, do you get a good quality recording?
Alex