I took delivery of an Audiomoth 1.2.0 just less than a week ago and yet I am still having issues getting the recordings that I want ... or at least expected. I'm a retired IT engineer (40 years and old enough to have coded in 'C' :) ), with a couple of years experience in Bird sound recording and a good year or so's experience of 'nocmigging', so I thought that setting up the audiomoth would be a cinch. However it appears not to be so straight-forward, so apologies in advance if I have made some stupid 'newbie'assumptions and mistakes.
First mistake - Using the wrong type of USB cable - changed from a charging to a data cable
Second misstake - using the wrong type of microSD card (2 nights recording ending with a 'corrupted' SD card which needed re-formatting) - so purchased a Sandisk Extreme 64GB card
at the 3rd attempt, I got some recordings, but the files were of differing sizes and generally hadn't captured much in the way of bird calls or even household noises, apart from the first file, generated after the device started recording at 19:00
This was not what I had expected - as the config tool told me that the device would generate a series of files around 230Mb in size.
Question: Does the audiomoth only record when a sound is detected, or do I need to increase the sleep timing, the longer the recording?
Question: Is there an upper limit to the size of the recording?
As I am principally (at this stage) interested in bird calls, I have set the Audiomoth to filter on sounds in the range 1.5kHz to 12kHz (approx).
Question: Does this model (v 1.2.0) only record up to 24kHz and if so, how are people using it to record bats, which apart from Noctules, will be broadcasting at higher frequencies than this?
I will try with a shorter recording period this evening, but ideally I would rather have a series of files 30 mins or so in length to process in Audacity, rather that a lot of files 5 mins in length.
Thanks in advance for any help with this! :)
It more of a question on the Nocturnal Flight Call - how to configure my AudioMoth V1.1.0 to record Migration Flight Calls. Would Alex or Charlie know and tell me how to configure and expect as a result.
My normal configurations Sample Rate 48, Gain Medium. My files are set at 5 sec sleep and 295 sec recording (5 minutes files). I’m OK with recordings of birds in the forest - but I have no exeperience with Night Migration of Birds.
Thanks.
Thanks Alex. I think that I have got the hang of things now. I did see a repeat of the above behaviou on another evening, where the initial recordings were of the correct length and then there were further recordings of various lengths until the rechargeable batteries gave out. I agree with your analysis that the behaviour is consistent with the batteries needing to be recharged.
I have now purchased some new rechargeable batteries and the Audiomoth is producing files of the anticipated length and size, providing I keep the batteries charged up.
Thanks very much for taking the time to answer my query. 😀
Hi Charlie, You can use the SanDisk Extreme cards straight from the packet without reformatting as AudioMoth will support both FAT32 and exFAT file formats. I'm not sure why your initial files are all different lengths. Can you share the CONFIG.TXT file that the AudioMoth wrote to the SD card. It looks like you set a record duration of 2500 seconds and a 5 second sleep duration. The first file is okay and then the files start to get shorter, although they are still all starting at the correct time. The most likely explanation is the batteries are running down so the AudioMoth stops the recording early due to the voltage dropping under the threshold during recording. The reason for the files being short will be written into the comments section of the WAV file header and you should be able to see this under 'Get Info' on a Mac, or in your WAV file viewer on Windows. Alex
OK, so having put this down in writing, I played around with the configuration and noticed that when I increase the sample rate, the frequency range that I can filter on, increases. Apologies if this was evident to other users, but it certainly wasn't to me ... and my physics degree was a long time ago. Doh! So that kinda answers my question on how I could use the AudioMoth to record Bat sounds.
On the SD Card page of the 'Getting Started' section, I read this:
From AudioMoth firmware version 1.2.2 onwards both FAT32 and exFAT file formats are fully supported. However, if you are using an earlier version of the AudioMoth firmware ensure that your SD card is reformatted as a MS-DOS (FAT32) card prior to use, or reflash you AudioMoth to use the newer firmware (see instructions here).
As I have a new Audiomoth and Firmware version 1.5.0, I guess that my device can support cards formatted with exFAT and I presume also that this means that the 32GB card limit is also removed as I'm using a 64Gb card and at least managed to get some recordings generated.
Re-configuring and putting the device out in the garden for another spin.