Detection of the high frequency clicks bats emit must be done with an ultrasonic transducer for two reasons.
Ultrasonic bat detector circuit.
Firstly such transducers are very responsive to ultrasound and thus produce large output voltages upon detection as compared to a generic audio microphone.
Heterodyning and frequency division are real time methods i e.
The detecting device used here is an ordinary electret condenser mic.
Software is optimised for power saving and speed by using asynchronous classification.
As you probably know bats emit ultrasonic sounds for the purpose of echolocation.
This project is about building a so called bat detector i e.
The sound from the detector is heard at the same time the call is emitted by the bat.
By down converting the ultrasound into our audible range we can indirectly detect it and at least enjoy a window into the hidden world of echolocation.
It has been suggested that bats utilize delay times arrival time differences and the doppler effect to interpret echoes.
That s where the bat detector comes in.
Heterodyning is the most sensitive method of the two but only transforms a small portion of the ultrasonic frequency range.
The figure above shows a simple ic 741 based ultrasonic sound sensor alarm circuit.
The mic input is fed to the inverting input of the ic pin 2.
A device that lets you listen to and record the sounds emitted by bats.
These sounds lie in a frequency range above the human audible range and thus can t be heard directly.