Heterodyne Bat Detector Circuit

Electronics page of yasushi sugimoto which includes some bat detector designs.

Heterodyne bat detector circuit.

A heterodyne function is often also built into the other types of detector. A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called heterodyning which was invented by canadian inventor engineer reginald fessenden. The advantage of this type is that you can listen to the bats in real time. Nevertheless the sounds heard with this detector are highly informative with real scientific value.

Heterodyning is used to shift one frequency range into another new frequency range and is also involved in the processes of modulation and demodulation. This means that realistic sounding calls are heard but bear in mind that they have been frequency shifted and are representative artifacts of the original sounds. There are three basic types of bat detectors see in this case i developed a heterodyne detector. This is a schematic for a straightforward direct conversion heterodyne detector having a tuning range of about 10 khz to 120 khz.

The by far most popular method for bat detectors appears to be the heterodyne down converting if you judge by the number of commercial and home built circuits frequency compression or time lapse this is the most advanced technology based on digital signal processing of the sampled bat sounds but it also requires the most advanced electronics. Problems with feedback will be smaller while the total gain of the bat detector is doubled. Heterodyne detectors are great for beginners but professional bat workers will also turn to the more technologically advanced models which allow extensive recording and. Hand held or passive and type of technology heterodyne fixed frequency time expansion or full spectrum.

The disadvantage is that using a heterodyne detector it is more difficult to distinguish different bat species compared to a high frequency recording. Another heterodyne detector from japan. A heterodyne function is often also built into the other types of detector. Circuit is still experimental.

Bat detector choices are influenced by factors such as your experience the mode of operation that you want e g. Heterodyne detectors bd16913 and bd4066 by cosy muto jh5esm. This heterodyne bat detector was built with a circuit similar to the one above except i experimented using ics for the first amplifier stages instead of transistors. A heterodyne bat detector simply shifts all the ultrasound frequencies downward by a fixed amount so we can hear them.

Heterodyne detectors are the most commonly used and most self build detectors are of this type. The first stage is a lm358 op amp with an adjustable gain trimmer and the second stage is a lm386 set up for 20 gain. à l écoute des chauves souris daniel dufour s bat page that shows a layout for a tca440 heterodyne bat detector.