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| The input frequency is divided by 32 using a CMOS counter type HEF4024 as shown above | |
| The output from the counter is a square wave at 1/32 of the input frequency. For a pipistrelle at 40kHz this gives an output of 1250 Hertz. Bat sounds lie in the range 20kHz - 200kHz approximately and dividing by 32 brings this to 625Hz to 6250Hertz. These frequencies are within the most sensitive part of the human hearing range, and also well suited to reproduction with a small loudspeaker or headphones. | |