Recordings and Files

Audio file ”xxxx_xxxxxxxx_xxx.wav”

After recording, a so-called WAVE file is saved to the internal hard disk under the file name “xxxxxxxxxx.wav” in a standardized audio file. (Example 0001_2e1709263_Test0001.wav)

  • The first 4 digits are the serial number of the device.
    • here: 0001
  • The next digit identifies the recording microphone number
    • here: 2 for channel / Mic 2
    • an M stands for manual recording
    • an A, B, C or D for a recording group
  • The next letter indicates whether it was recorded before midnight (e = Evening) or after midnight (m for Morning). This is mainly used for the meaningful alphabetical sorting of file names in directories.
    • here: e for Evening
  • The next 6 digits indicate the recording time
    • here 17:09:26
  • The next digit is just a number, which makes sure, that the file name is unique, if there are several recordings during the same second on the same channel
    • here 3
  • The last part of the file name is the project ID configured by the user.
    • here Test0001
  • The .wav extension identifies a WAVE file.

The .wav file essentially contains the entire measured values as “raw data” (without compression) and a format-specific “header”, which also contains the sampling frequency.

Simultaneously with these recording data, an information file (.xml) with all recording data (metadata) is saved under the same file number (see below).

The recordings are stored in subfolders on the BATLOGGER. The subfolders are sorted by year, month and day. A new folder is created every night:


The .wav files can be read with various audio programs or with bat-specific sound analysis software and displayed as time signal or spectrogram.

Recording information 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.:

<?xml version="1.0" encoding="utf-8"?>
  <Firmware>1.0.14</Firmware>                                         Firmware version
  <SN>1</SN>                                                          Serial number (last 4 digits)
  <SNfull>21621317290001</SNfull>                                     Full serial number
  <Alias>Test0001 Michael, Lappach</Alias>                            Alias
  <ProjectID>Test0001</ProjectID>                                     Project ID
  <Filename>0001_2e170926_Test0001.wav</Filename>                     The file name of the WAVE file
  <DateTime>04.01.2018 17:09:26</DateTime>                            Recording date and time
  <Timezone>Europe/CET</Timezone>                                     Set time zone
  <Duration>3 Sec</Duration>                                          Duration of recording in seconds
  <Samplerate>312500 Hz</Samplerate>                                  Sample rate
  <Resolution>16 Bits</Resolution>                                    Bits per sample
  <Temperature>4 C</Temperature>                                      Temperature
  <Position>48.217819 12.113530</Position>                            GPS position
<TriggerSource>automatically triggered</TriggerSource>        Triggers
<Microphone>                                                          Data of the recording microphone
  <WavTrackNo>1</WavTrackNo>                                   Track number in WAVE File
  <MicChannelNo>2</MicChannelNo>                                      Microphone number (channel)
  <HasTriggered>1</HasTriggered>                                      This microphone has triggered
  <Gain>12 dB</Gain>                                                  Adjusted gain
  <MicConnected>Yes</MicConnected>                                    Microphone was connected
  <SerNo>21651117290032</SerNo>                                       Serial no microphone
  <Manufactured>29/2017</Manufactured>                                Date of manufacture of the microphone
  <LastCalib>31/2017</LastCalib>                                      Last calibration date
  <MicTemp>4 C</MicTemp>                                              Microphone temperature
<TrgSettings>                                                         Trigger conditions settings
  <MinFreq>17000</MinFreq>                                            Minimum trigger frequency
  <MaxFreq>160000</MaxFreq>                                           Max trigger frequency
  <CrestFactor>8.00 (32, 0x20)</CrestFactor>                          Minimum crest factor
  <FFTVal>5.000 (320, 0x140)</FFTVal>                                 Minimum FFT
  <PeriodTrig>1</PeriodTrig>                                          Max period trigger value
  <MinSoundLevel>1% (328, 0x148)</MinSoundLevel>                      Minimum volume
  <PreTriggerTime>500</PreTriggerTime>                                Pre trigger in ms
  <PostTriggerTime>800</PostTriggerTime>                              Post trigger in ms
  <MaxGapTime>900</MaxGapTime>                                        Max gap between calls
  <MaxDuration>15000</MaxDuration>                                    Max recording time in ms
<TrgValues>                                                           Actual values that triggered triggers
  <PeakFreq>22265</PeakFreq>                                          Trigger frequency in Hz
  <CrestFactor>17.75 (71, 0x47)</CrestFactor>                         Crest factor at trigger
  <FFTVal>87.953 (5629, 0x15fd)</FFTVal>                              FFT at trigger
  <PeriodTrig>1</PeriodTrig>                                          Periode trigger value at trigger
  <MinSoundLevel>38% (12540, 0x30fc)</MinSoundLevel>                  Sound level at trigger
  <FrameIndex>155648 (BlockIdx:152)</FrameIndex>                      Frame in wav file

Log file “BATREC.log”

When the device is operated, a log file (text file) called BATREC.log is automatically written to the user’s main directory on the system hard disk. Each line of text entered is preceded by the serial number (SN) of the device that created the entry. The BATREC.log is continuously updated in the main directory of the user data.

Deleting.wav files in the logger does not affect the BATREC.log.

The BATREC.log lists all activities, especially error situations and statuses of the device chronologically. Events are recorded with date and time if the system already has a system time available.

Example BATREC.log:

SN0001 01.01.1970 01:00:10  - INFO: ********************* START FROM BOOT ************************
SN0001 01.01.1970 01:00:10  - INFO: BATLOGGER serial number: 21621317290001
SN0001 01.01.1970 01:00:10  - INFO: BATLOGGER ethernet MAC address: AC:1D:DF:D0:00:01
SN0001 21.12.2017 17:20:57  - INFO: System time set by RTC
SN0001 21.12.2017 17:20:57  - INFO: BATLOGGER Core software version: 1.0.14
SN0001 21.12.2017 17:20:57  - INFO: BATLOGGER PwrMgr version: 1.0.9, hardware version: 0
SN0001 21.12.2017 17:20:57  - INFO: User root has successfully changed login password.
SN0001 21.12.2017 17:20:57  - INFO: LTE Model: TOBY-L210
SN0001 21.12.2017 17:20:57  - INFO: LTE firmware version: 15.63
SN0001 21.12.2017 17:21:06  - INFO: System is up. Starting operation.
SN0001 21.12.2017 17:21:06  - INFO: Create MQTT client.
SN0001 21.12.2017 17:21:08  - INFO: Connection to MQTT server established
SN0001 21.12.2017 17:21:08  - INFO: Successfully subscribed to TB RPC calls
SN0001 21.12.2017 17:21:09  - INFO: RTC set!
SN0001 21.12.2017 17:21:09  - INFO: Initial data sent to MQTT server.
SN0001 21.12.2017 17:21:09  - INFO: Battery voltage: 7841mV, current: 87mA
SN0001 21.12.2017 17:21:09  - INFO: Channel configuration:
SN0001 21.12.2017 17:21:09  - INFO: Channel 1, device 1: Sensor:     ID: 29498120000000B6 SerialNo: 21621017290001 FW-Vers.: 3 Hum:yes AirP:yes
SN0001 21.12.2017 17:21:09  - INFO: Channel 1, device 2: Microphone: ID: 3B6D7E1F00000046 SerialNo: 21651117290033
SN0001 21.12.2017 17:21:09  - INFO: Channel 2, device 1: Microphone: ID: 3B723028000000BC SerialNo: 21651117290032
SN0001 21.12.2017 17:21:09  - INFO: End of configuration
SN0001 21.12.2017 17:21:09  - INFO: Waiting now for commands from UI
SN0001 21.12.2017 17:23:06  - INFO: UI authentication successful for user root.
SN0001 22.12.2017 02:13:49  - ERROR: Connection to MQTT server lost!
SN0001 22.12.2017 02:13:52  - INFO: Connection to MQTT server established
SN0001 22.12.2017 02:13:52  - INFO: Initial data sent to MQTT server.
SN0001 22.12.2017 02:13:52  - INFO: Successfully subscribed to TB RPC calls
SN0001 22.12.2017 10:05:41  - INFO: RTC set!
SN0001 22.12.2017 10:05:41  - INFO: RTC (re-)set by time retrieved from internet.

Daily user log file

Besides the system log file, the BATLOGGER writes a user log file daily. This is stored together with the recording files in the daily recording directory.

The name consists of the coded recording day (e.g. BL20180104 for 04.01.2018) and the project ID (see recording data). Example BL20180104_Test0001.csv

For the device with the project ID Test0001 on 01/04/2018.

The file is stored in .csv format, so that the data contained can be easily captured and visualized in programs such as Microsoft Office or Libre Office.

The user log file contains information about boot processes, switching recording times (events) on and off, number of recordings made and environmental data such as temperature, humidity or air pressure (if sensors are installed). Recording and environmental data are recorded every 15 minutes.

By this temporal rastering one can quite simply create a diagram in Excel, which shows the bat activity over the course of the night. These can then be correlated with the environmental data.