UTC time issue

Yep, I've been playing around copying files and changing timezones, and it's hard to understand exactly what macOS does, but the WAV file on the SD card and the TEST.TXT file have actual file creation times of 00:47 and 00:36. However, if you change the time zone between opening the SD card and copying TEST.TXT onto the SD card, you can end up with a permanent time offset between the two - in this case one hour

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Thank you that makes sense. I looked at the 'More info' tab once on my local drive and can see despite the WAV file displaying different times the recording times are the same (phew). When Im saving the csv files when performing analysis in Kaleidoscope it is time stamping each with the WAV file times so I will just manually correct this time in my excel files.

Yes, ignore the file creation and modification dates. The FAT and exFAT formats that the SD cards use don't allow any timezone information to be stored along with the times in the file directory and these times have to be written in local time or UTC. This becomes become confusing when timezones change as I think macOS tries to be helpful and converts the times again. Use the timestamp in the file name which in your screen shot above is 10:00 UTC on 19/3/21. The same timestamp is written in the header comments within the WAV file which will appear under the 'More Info' tab. The latter doesn't always appear immediately as the macOS has to open each file and read it to determine this information. Copying the file to a local drive typically forces this to happen.

The example above was recorded at 15:20 UTC with the timezone set to UTC+1 so the timestamps in the WAV header and the file name are formatted as UTC+1 and the CONFIG.TXT file will show the recording period as starting at 15:20 UTC.

When you say 'the WAV files are recorded as 11am-7:59pm' - how are you determining that - from the file name and the comment in the header, or from your computer reading the file creation and modification time? Can you show a screenshot of this? When you say 'I can manually change the times' - what times are you intending to change? The file names and the WAV header comments will show the recording time in the time zone that was specified when the device was configured. These are the times that the AudioMoth will have actually worked to.

Hi Alex, I am in Melbourne, Australia. The devices were set with the Config App. The times I am reading are with the WAV files. The audiomoths that were deployed on the 8/3/21 were set to record 10:00-19:00 (UTC) and WAV files are recorded as 10am-6:59pm (which is what I expected 9pm-5:59am local time), those on 13/3/21 were also set to record 10:00-19:00 (UTC) but WAV files are recorded as 11am-7:59pm. I did download files at two different time periods so it is possible the 8/3/21 files were downloaded prior to 4/4/21 (when daylight savings ended locally) and others after this date. So it sounds that is likely due to computer converting times on download? As long as I can be sure the data was recorded at the same times then that is ok and I can manually change the times

Can you confirm where you are based and how the devices were set - Config App or smartphone app? Where are you reading the times you are reporting - 10am - 6:59pm and 11am - 7:59pm? All the AudioMoth file name and time stamps (in the WAV header) will be in UTC, and the recordings will have started at the correct UTC time, if the values in the CONFIG.TXT file are correct. File creation times on the SD cards contain no timezone information which often causes problems. The AudioMoth writes the SD card creation and modification times using the local time zone that is requested in the configuration. I think your computer is converting the times you are looking at into local time with a summer time correction?