The aim of this project is to provide students and other naturalists interested in bat bioacoustics with a bat detector that is cost-efficient, but at the same time fulfilling semiprofessional needs.
Barataud (2015) is surely the most important book on the bioacoustics of bats. In his chapter on technical developments, he asks: „What improvements can we still dream of?“ and gives an answer himself: „First of all, some reduction in the price of these items. Let us hope that the constantly increasing number of naturalists interested in this field throughout the world will be paralleled by a corresponding fall in the market price of bat detectors, because good quality equipment is still prohibitively expensive.“ Well, this is exactly what the Teensy Bat Detector is meant to be: a cost-effective yet very powerful bat detector with heterodyne, time expansion, recording on SD, spectrum and spectrogram display etc. The price is one fifth to one tenth of the usual price you would pay for these features if you bought a commercial detector. However, there is a price you have to pay: Do-It-Yourself ! You build the components together and you provide the battery, push buttons and a case. That´s all! Additionally, the Teensy Bat Detector is one of the few bat detectors with open source software and can easily be extended and upgraded by software with very simple Arduino programming tools.
For semiprofessional use, a bat detector must be able to do the following (and the Teensy Bat Detector can actually do all that ;-)):
- Heterodyne frequency translation
- Time expansion by playback of ultrasonic recordings in slower speed
- Record ultrasound on SD card for later analysis with computer software
- Spectrum display of the ultrasound (frequency vs. Audio power level)
- Spectrogram display = waterfall display (frequency vs. Time vs. Audio Power level)
What is the difference between a professional bat detector and the Teensy Bat Detector ?
- The microphone used in the Teensy bat detector is a very cheap electret microphone which does not span the whole frequency range used by bats
- Highest possible sample rate setting of 192ksps gives a possible highest detection frequency (if the mic allows this) of 96kHz, which is quite high, but not high enough to allow detection of all the bat species (eg. horseshoe bats, highest parts of Myotis species calls)
- At the moment, recording is possible in high quality at 96ksps, but with higher sample rates there is some digital noise involved
- 0 to 96kHz frequency span (96kHz is possible only with a suitable microphone)
- Heterodyne detection = audible audio in realtime
- Automatic Bat peak frequency display in heterodyne mode
- Spectrum display
- Spectrogram as waterfall display
- Record function of the total audio spectrum for further analysis on the PC
- Playback = time expansion function of the recorded files
- Costs: under 100,- € including case and battery (a little cheaper in the USA, because you can order the Teensy parts directly at PJRC: http://www.pjrc.com/store/teensy36.html)
- Realtime frequency translation