Config App Estimation Question
Hi, I’m setting up an AudioMoth for a 2-week bat monitoring deployment in Texas and wanted to confirm that I have the configuration set up correctly for what I’m trying to accomplish.
My current settings are:
Sample rate: 250 kHz
Gain: Medium
Schedule: Sunset to Sunrise
30 minutes before sunset
30 minutes after sunrise
Sunrise/sunset rounding: 1 minute
Filtering:
Trigger type: Amplitude
Filter type: High
Recordings filtered to frequencies above 16 kHz
Minimum trigger duration: 2 seconds
Amplitude threshold: 0.002%
My goal is to capture bat activity while minimizing data storage so the unit can remain deployed for approximately 2 weeks.
What is making me question whether I have something configured incorrectly is the storage estimation at the bottom of the Configuration App. It reads:
“Recordings will exceed the 4.3 GB max size of wav. file so will be split.”
When I click on the estimation panel, it says:
“Each day will produce 6 files, each up to 4295 MB, totaling up to 23 GB.”
Given that I’m using amplitude-triggered recording, is this ~23 GB/day estimate simply a worst-case calculation based on the total scheduled recording time at 250 kHz, rather than an estimate of the actual size of the triggered T.WAV files? With these settings, should I expect the recorder to save only triggered bat events and therefore be able to remain deployed for 2 weeks, assuming normal bat activity and sufficient SD-card capacity?
Also, in the Advanced tab, should I enable Energy Saver Mode for this deployment, or could that negatively affect recording quality or trigger detection with these settings?
I’d appreciate any feedback on whether you would change anything in this configuration for a general bat monitoring deployment. Thanks in advance for your time!
Hi, Yes, the 'up to' means that in the worst case each file might be 4295 MB in size. We would recommend that you also use cyclic recording - something like record for 59:55 and sleep for 00:05. This will mean that the file size is more manageable, and each file will start at the start of each hour, rather than stopping and starting when the file size limit it reached. Energy saver mode improves energy consumption with a small loss in recording quality. It only has an effect at sample rates of 48 kHz and below so will be ignored. The amplitude threshold of 0.002% is very low and I'd expect the AudioMoth to continually trigger with background and self noise at that setting. An initial test deployment at 2% is probably safer. If you already have non-triggered recordings, you can load them in AudioMoth Play (https://play.openacousticdevices.info/) and try out different trigger settings.
The biggest variation in energy consumption is caused by the SD cards. At high sample rates, some cards can use 2 or 3 times as much as others. See the table and application note below.
https://github.com/OpenAcousticDevices/Application-Notes/blob/master/A_Comparison_of_SD_Card_Energy_Consumption/A_Comparison_of_SD_Card_Energy_Consumption.pdf Finally, make sure you use good quality alkaline or high-capacity (>2500 mAh) NiMH batteries. If you can test the settings overnight in a similar environment before the full deployment to check that the trigger settings aren't too sensitive. The red LED will flash about once per second whilst waiting to trigger. When it is actively recording it will flash very quickly and appear nearly continous. You can trigger that by rubbing your hands together in front of the microphone to generate ultrasonics. Alex