Chirp Mode: System Testing

About this task

This method of testing does not use the Test microphone window at all, and it is not intended to give a precise measurement of microphone sensitivity. Instead, it involves generating loud, ultrasonic chirps that superficially resemble those produced by a bat. When the Song Meter Mini Bat 2 is set up for triggered, ultrasonic recording, these ultrasonic chirps should trigger the recorder to begin recording and save the resulting files to its SD card. This can be useful if the Song Meter Mini Bat 2 is mounted out of reach.

CAUTION:

Do not place the Ultrasonic Calibrator near your ears! In CHIRP mode, the calibrator emits a 40 kHz signal at over 100 dB SPL. Prolonged exposure to high-intensity ultrasonic signals may cause permanent hearing loss at audible frequencies.

Procedure

  1. Program the Song Meter Mini Bat 2 with a recording schedule that will have the recorder awake and running an ultrasonic recording period during the test.
  2. Place the recorder no more than 20 m (65 ft) away from the Ultrasonic Calibrator.

    If the Ultrasonic Calibrator is held very close to the microphone, the calibrator signal may be too loud for the Song Meter Mini Bat 2 to record correctly. The recorded signal will be distorted, and artificial harmonics will be present in the resulting recording.

  3. Set the calibrator's mode switch to CHIRP.

    The calibrator emits a 100 ms, 40 kHz (± 10 Hz) tone every 500 ms. The amplitude of the tone is 104 dB SPL (± 3 dB) at 10 cm.

  4. Observe the Status screen for the paired recorder. As the recorder saves audio files to the SD card, the RECORDINGS tally will increase. Depending on the recorder's Maximum Recording Length setting, it may take up to a minute for the RECORDINGS tally to increase.
  5. If you view the recordings in a spectrogram viewer like Kaleidoscope Pro Sound Analysis software, you should see periodic pulses at 40 kHz.