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ABC Bat detectors

 

So, starting with bat research? Going to choose the best detector for own project? 

We do have solution - our guide "How To - ABC Detectors" should answer all questions. If not - just ask a question - we will answer as soon as possible...

 

A bat detector is an indispensable tool for anyone studying bats in the field. The detector enables you to hear the otherwise inaudible ultrasonic calls of the bats. This is most useful to identify different species as well as just determining bat activity.

The bat detectors from Pettersson Elektronik are high quality instruments, designed in close cooperation with leading bat workers for optimum performance and durability .

The transformation of ultrasound into audible sound can be made with different techniques. The most common are:

 

Heterodyning
Frequency division (count-down)
Time expansion

 Heterodyning and frequency division are real-time methods (i.e. you will hear the sound from the detector at the same time it is emitted by the bat). Heterodyning is the most sensitive method of the two but only transforms a small portion of the ultrasonic frequency range. The user selects the range to transform with a tuning control. Some of Pettersson Elektronik´s more advanced detectors have an automatically scanning heterodyne system which eliminates the need of manual tuning.

The frequency division method transforms the entire ultrasonic frequency range without tuning. In a frequency division detector, the frequency of the ultrasound is divided by a constant factor, e.g. 10, meaning that a frequency of 50 kHz will be converted to 5 kHz. All of Pettersson Elektronik´s frequency division detectors are of the more advanced retained amplitude type. This means that the amplitude of the transformed signal follows that of the original ultrasonic signal.

The time expansion method is similar to making a high speed tape recording of the sound and then playing it back at a lower speed, however in time expansion detectors digital techniques are used to store the signal instead of a large and expensive high speed tape recorder. Obviously this is not a real-time conversion method, but in return it offers a number of important advantages. Since the signal is stretched out in time,  it is possible to hear details of the sound not audible with other methods (e.g. you can actually hear frequency differences within one short pulse or between different pulses). Time expansion is also the only technique that preserves all characteristics of the original signal, making time expanded signals ideal for sound analysis in the laboratory.

 

AnaBat system

The AnaBat bat detector system is used to identify species of bats by detecting, recording and displaying their ultrasonic echolocation calls. AnaBat detectors can be used in two principal ways - to monitor bat activity in the absence of a human operator (Passive Monitoring) or to produce realtime sonograms of calls to aid identification of bats in the field (Active Monitoring). For passive monitoring, calls can be stored to Compact Flash cards, with a single card capable of storing data for several weeks or even months. For active monitoring, the detector needs to be interfaced to a PDA (palmtop) or laptop computer by a device called a ZCAIM.

Typical monitoring approaches using Anabat
Short-term passive monitoring
Monitoring Stations (Long-term Passive Monitoring)
Active monitoring
Mobile surveys