Recordings and Files¶

Audio file ”xxxxxxxx.wav”¶

Under the file name “xxxxxxxx.wav”, the recorded data is saved in a standardized audio file, a so-called WAVE file, on the microSD card. (Example 10160435.wav) The first 4 digits are the device number of the BATLOGGER and the other 4 digits are a consecutive numbering of the recording files on the inserted microSD card. The example above is therefore the 435th recording on this microSD card from the BATLOGGER with the device number 1016. The .wav file essentially contains the entire measured values as “raw data” (without compression) and a format-specific “header” which, among other things, also contains the sampling frequency. Additionally, the file contains another sub-chunk for GUANO metadata (see below). At the same time as this recording data, an information file (.xml) with all recording data is saved under the same file number (see below). The recordings can optionally be saved in subfolders (daily, weekly, monthly, per start). The .wav files can be read with various audio programs or with bat-specific sound analysis software and displayed as time signal or spectrogram. The latter is the most reliable way to determine the species.

GUANO metadata¶

GUANO is a cross-device standard for storing bat detector metadata directly in the .wav file. Further information can be found at https://guano-md.org. The guano subchunk is at the end of the file. BATLOGGER-specific data is stored under the namespace “BATLOGGER”.

Example:

GUANO|Version: 1.0
Make: BATLOGGER
Model: M2
Firmware Version: 1.0.0
Serial: 1001
Original Filename: 10010003.wav
Timestamp: 2019-01-21T22:14:29
Length: 7.02
Samplerate: 384000
Temperature Ext: 23
BATLOGGER|Trigger|Frequency: 52

Recording metadata file ”xxxxxxxx.xml”¶

For each “xxxxxxxxxx.wav” file stored, an additional information file “xxxxxxxxxx.xml” is stored with the same number with various metadata on recording time, date, location, temperature and device settings (parameters).

Example of the content of an .xml info file.:

<BatRecord Model="M2" Rev="1">
  <Firmware>0.1.3</Firmware>
  <SN>0004</SN>
  <Filename>00040000.wav</Filename>
  <DateTime>06.05.2020 21:01:39</DateTime>
  <Duration>1.5 Sec</Duration>
  <Samplerate>384000 Hz</Samplerate>
  <Temperature>24.0 C</Temperature>
  <BattVoltage>4.1 V</BattVoltage>
  <GPS>
    <Valid>yes</Valid>
    <Position>47.04678 8.30131</Position>
    <Altitude>438 m</Altitude>
    <SatsUsed>4</SatsUsed>
  </GPS>
  <Microphone>
    <MicChannelNo>0</MicChannelNo>
    <Gain>2 dB</Gain>
  </Microphone>
  <TrgSettings>
    <MinFreq>15000</MinFreq>
    <MaxFreq>192000</MaxFreq>
  </TrgSettings>
  <TrgValues>
    <Event>sound</Event>
    <PeakFreq>32250</PeakFreq>
    <CrestFactor>12.63</CrestFactor>
    <Level>28138.9 dB SPL</Level>
  </TrgValues>
</BatRecord>

Track-Datei ”xxxxxxxx.gpx”¶

In Explore and Transect applications, the route covered is recorded as GPX track file. The GPX file name is corresponds to the current recording number (example 10160435.gpx) and is created at the start of the recording session. It is then continuously supplemented with the current GPS position. The recording is stopped as soon as the recording session is left. When starting a new recording session, a new file is created or, if no recording has been made since the last start, any existing GPX file is continued. The GPX file contains the route covered as a so-called track. It is based on the XML standard and can be opened with e.g. Google-Earth and all common GIS programs.

Bat entry and exit counter “BATCOUNT.csv”¶

The Counter profile can be used to count bat entries, exits or other activities. For each count value an entry is written to the file “BATCOUNT.csv” in the root folder with timestamp, direction / status, current number, temperature and location (if available).:

Timestamp,State,Count,Temperature [°C],Latitude [WGS84],Longitude [WGS84],Altitude [m]
09.2018 19:26:20,Start,0,26,47.053330,8.257547,467.9
09.2018 19:26:23,Out,1,26,47,053330,8,257547,467.9
09.2018 19:26:23,Out,2,26,47,053330,8,257547,467.9
09.2018 19:26:24,Out,3,26,47,053330,8,257547,467.9
09.2018 19:26:25,In,1,26,47,053330,8,257547,467.9
09.2018 19:26:27,Out,4,26,47,053330,8,257547,467.9
09.2018 19:26:27,In,2,26,47,053330,8,257547,467.9
09.2018 19:26:29,Out,5,26,47,053330,8,257547,467.9
09.2018 19:26:30,Out,6,26,47,053330,8,257547,467.9
09.2018 19:26:32,End,4,26,47,053330,8,257547,467.9

Activity statistics “BATSTAT.csv”¶

When used, the BATLOGGER automatically saves a statistics CSV file (Comma separated values) with the name “BATSTAT.csv” in the root folder of the SD card. The file is extended with new data if it already exists. Every hour, a new line is added to the file containing the number of recordings made in the last hour. In addition, temperature and battery data is stored. To use this data, load the file into a spreadsheet application (Excel).:

Timestamp,Status,Recordings,Temperature [°C],Battery [V],Charge [V],Charge [A]
06.2018 21:00:00,Listening,22,26,4.15,11.80,0.47
06.2018 22:00:02,Listening,154,27,4.15,11.80,0.30
06.2018 23:00:00,Recording,131,26,4.15,11.80,0.24
06.2018 00:00:00,Listening,15,25,4.15,11.80,0.23
06.2018 01:00:00,Listening,24,24,4.15,11.76,0.22
06.2018 02:00:00,Listening,6,23,4.15,11.76,0.21
06.2018 03:00:00,Listening,7,21,4.15,11.76,0.21
06.2018 04:00:00,Listening,5,21,4.15,11.80,0.21
06.2018 05:00:00,Listening,13,21,4.15,11.80,0.21

Log file “BATREC.log”¶

When in use, the BATLOGGER automatically writes a log file “BATREC.log” in text format to the SD card. Everytext line is preceded by the serial number (SN) of the BATLOGGER writing the log. When changing the SD card to another logger, or removing it and re-inserting it again, the log file will be extended and new log information appended to the “BATREC.log” file. Deleting WAVE files through the menu of the BATLOGGER does not affect the “BATREC.log” file. However, formatting the SD card will also erase the “BATREC.log” file! In the file ”BATREC.log”, all activities of the BATLOGGER are listed chronologically.

Example log file.:

SN0004 10.09.2020 20:14:42 I Startup (FW0.1.45, 160300_b)
SN0004 10.09.2020 20:14:46 I Updated RTC Date/Time from GPS to 10.09.2020 18:14:46 UTC. Difference: -160 ms
SN0004 10.09.2020 20:14:47 I Profile 'Erkunden' started
SN0004 10.09.2020 20:14:47 I Record mode started
SN0004 10.09.2020 20:14:47 I Create TrkFile /BL20200910/00040072.gpx
SN0004 10.09.2020 20:14:50 I Updated RTC Date/Time from GPS to 10.09.2020 18:14:50 UTC. Difference: 176 ms
SN0004 10.09.2020 20:55:46 I Profile 'Erkunden' stopped
SN0004 10.09.2020 20:55:46 I Record mode stopped
SN0004 10.09.2020 20:56:40 I Shutdown