DIY Bat Detector with Gamification Elements

Abstract

Bats use ultrasonic sounds for orientation and hunting. Their frequencies are outside the human hearing range. However, theese sounds can be made audible with detectors and digital transducers. For a first practical and interdisciplinary science approach in schools, commercial detectors with digital data acquisition are useful (e.g. Echo Meter Touch 2 plug-in module for smartphones). With the connected app, they can display spectrograms. A stored database compares the sounds and indicates the most likely bat species.in real time.
For a low-cost alternative and additioonal motivation via gamification elements, we have developed a DIY kit that can be manufactured with modern maker tools. In addition to the acoustic conversion of ultrasound into audible sound, the prototype also contains visually and haptically perceptible signals and resembles a game pad in function and form. The poster presents the physical and technical aspects of this detector.

Full text

Prof. Dr. Lutz Kasper1 | Dr. Ann-Katrin Krebs2 | Jochen Pfeifer1 | Dr. Hannes Helmut Nepper1
1University of Education Schwäbisch Gmünd (Germany) | 2Leuphana University Lüneburg (Germany)
DIY Bat Detector with Gamification Elements
1. Interdisciplinary Perspectives: Biology, Physics, and Technology
2. DIY- and Gamification Approach
potentiometer
(frequency or volume)
switch!
(vibration on/off)
battery
signal input!
(ultrasonic microphone)
optical signal!
(LED eyes)
AUX / headphones,!
bluetooth adapter
potentiometer
(frequency or volume)
switch!
(vibration on/off)
Access via Physics and Technology: Oscillations, Waves and Engineering Objects
Some devices can display, visualize and save the measured frequencies directly. Artificial
ultrasonic sources such as distance sensors, ultrasonic toothbrushes or the autofocus
function of photo lenses with ultrasonic drive can also be examined using the echo meter. With
its measuring range of 20-192 kHz, the detector also records such "inanimate" ultrasonic
sources.!
To test the bat module, we operated an ultrasonic transmitter with a sine wave generator at a
frequency of 34 kHz. As expected, the detector displays a strong, continuous signal at the
specified frequency (see Fig. 4). The widely used HC-SR04 ultrasonic module, on the other
hand, behaves very similarly to a bat. This module is often used, for example, in combination
with the open Arduino platform in DIY projects (see Fig. 5). The measurement with the bat
detector shows clear differences to the continuous signal in Fig. 4. The HC-SR04 emits burst
signals with a frequency of 40 kHz and a pulse length of 200 μs each. This is clearly shown in
the sonogram (Fig. 6).
Biological Access
Bats are found almost worldwide. With around 1400 species in 200 genera and
19 families, they are the second largest mammalian order and make up 20 % of
known species. Bats are the only land-dwelling and flying mammals that use
echolocation. Ultrasonic detectors can be used to record their calls in the
frequency range from 20 kHz to 140 kHz (see example in Fig. 2). Bats also use
ultrasound to hunt insects. Depending on the species, they emit ultrasonic
signals from their mouth or nose. To do this, they press air in their throat over
the stretched vocal folds, which vibrate and produce their calls. The animals use
the acoustic Doppler effect for orientation and hunting, as they and their prey
Adaptation of the B@t detector kit
Normally, do-it-yourself kits for bat detectors involve soldering or plugging components onto a
prefabricated circuit board and are only suitable for young people aged 14 and over. The newly
designed and developed B@t detector (Fig. 7) is also adapted for younger children (e.g.
elementary school), but uses the same circuit board.In addition, inclusive aspects of sensory
perception are incorporated so that not only acoustic but also visual and haptic signals are
emitted during detection. This makes the detector similar to a gamepad.
Further technical development
Based on the desired additional functions for simulating a gamepad, a new circuit board with
additional components must be developed for the detector and manufactured as a prototype
(Fig. 8 and 9). The individual steps are presented in the block diagram below.
Output functions
•conversion of ultrasound
into audible sound;!
•output via loudspeaker;!
•status LED
1st Implementation
•synchronous visual
feedback;!
•synchronous haptic
feedback
2nd Implementation
•inverted optical feedback!
•integration in status LED
1st Optimization
•minimization of software
drivers
2nd Optimization
•integration of two functions
in one driver!
•synchronous control &
inversion
Further development
•production of a prototype;!
•debugging; !
•testing with students and
pupils
Objective definition
•insulation-milled PCB for
wired components; !
•versions with/without sockets!
•SMD version, fully integrated
5th Optimization
•enhanced routing
4th Optimization
•reduction in overall height
3rd Optimization
•connection of the
components via coded plug
connections
Fig. 1: Broad-winged bat (Eptesicus serotinus)!
(photo: A.-K. Krebs)
Fig. 2: Screenshot of an acoustic signal of the broad-
winged bat (Echo meter app)
Fig. 4: Screenshot of a continuous
technical ultrasound signal (Echo meter
app)
Fig. 5: plug-in bat detector
(echo meter) mounted on a
smartphone
Fig. 6: Screenshot of the ultrasound
signal from distance sensor HC-SR04
(echo meter app)
Fig. 3: Link to
audio sample
and video of an
active bat
References
Krebs,%A.‑K., Kasper,%L., Kuhn,%J. & Wilhelm,%T. (2022). Mit Echo Meter auf Fledermauspirsch. In: Physik in unserer Zeit, 53(2), 96–97.
https://doi.org/10.1002/piuz.202270212!
Pfeifer, J., Krebs, A.-K. & Nepper, H. H. (2023, submitted). Konstruktion und Fertigung eines Fledermausdetektors.
Gestaltungsgrundlage für die Initiierung immersiver Lernumgebungen. In: TU - Zeitschrift für Technik im Unterricht.%
Fig. 7: 3D body of the B@t detector with components and description (design: A.-K. Krebs)
Fig. 8: circuit diagram
Conversion into audible sound takes place in bat detectors and is perceived from the
loudspeaker as a partially slowed-down "rattling" sound. An audio example with a combined
video recording of a bat can be found under the QR code (Fig. 3).
Fig. 9: Functional description of the circuit