If you have made a Raspberry Pi bat recorder/detector, you will want to test its functionality. Without bats around to try it, you’ll need to simulate bat calls.
The best device for simulating bat calls is Tony Messina’s Bat Chirp. His website also has details on making bat detectors. A recent search for the Bat Chirp was unsuccesful – it may have been removed from his site.
An (inferior) alternative can be made quite cheaply with an Arduino Pro Mini, a 40kHz Ultrasonic Transmitter and 3 AA batteries. The Arduino can be programmed to emit ultrasonic test pulses that can be used to check the functioning of a bat recorder/detector.
Circuit diagram of the Bat Simulator:
Bat Simulator video
Video of the Bat Simulator in action. A heterodyne Bat Detector is being used to playback the sound, and the Multi-Function Raspberry Pi Bat Recorder/Detector is being used to display the frequencies.
Bat Simulator Spectrogram and Peak Frequency Graph:
The spectrogram and peak frequency graph of the simulated bat calls shows the range of frequencies produced:
Contact me if you are interested in making a Bat Simulator. Here’s one in a small, slim project case (6.5cm x 6.5cm x 1.9cm).