Bat Detectors

  
The D100 detector

The D200 detector series

The D1000X detector

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. An example of this is shown to the right.

The upper signal is the original ultrasound, while the lower is the frequency division output 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.

If you need more information, please contact Pettersson Elektronik at info@batsound.com

The D 1000X Detector

 

·       Heterodyne, frequency division and time expansion systems

·       Uses a CF-card to store the signals as “wav” files

·       Recording and playback at sampling rates from 32 to 768 kHz

·       16-bit Analog-to-Digital converter for increased dynamic range

·       Integrated, adaptive anti-aliasing filter

·       Manual or level-triggered modes – unattended recording possible

·       Accurate recording level indicator

·       Recording time limited by available CF-card space only

·       Adjustable LCD background and LED intensity

·       Battery and CF space indicators

·       Small size – 170 x 80 x 35 mm excl microphone

·       Low weight – 600 g incl batteries

·       Powered from internal batteries or external power supply, 7-10V

The D-1000X is the first bat detector with a built-in “tape recorder”, relieving the user from the hassle of operating a separate tape recorder or laptop with connecting cables. It can be configured to work in a variety of operating modes, but thanks to the use of “Profiles”, switching between different modes is made instantly. Each profile contains all the selectable settings such as sampling rate, triggering mode, time expansion factor and LED intensity and can be prepared in advance and saved in the detector. 

At any time, either the direct ultrasonic signal, the heterodyne signal or the frequency division signal can be recorded onto the CF-card. Spoken comments can be recorded by speaking into the microphone while recording in the direct mode, or in a special comment recording mode (at a lower sampling rate). The recording time is limited only by the available space on the CF-card. Upon completion of a recording in the direct mode, the signal will be automatically replayed in time expanded form, if this function is enabled. Time expansion factors from 1 (original speed) to 30 can be chosen. The recordings can be made by manually starting and stopping the recording or through level-activated (and optional frequency selective) triggering. In the latter case, the detector can be set up for unattended capture of calls. Pre- and post-triggering modes with a variety of different settings can be used.

The wav sound files on the CF-card are stamped with date and time and can be read directly on a PC, using a standard CF-card reader. The D1000X also has a serial (RS232) GPS input, making it possible to save GPS position data in the files.

Technical specifications D100

Pettersson Elektronik AB
Dag Hammarskjolds v. 34A
S-751 83 UPPSALA
Sweden
Tel: +46 1830 3880 Fax: +46 1830 3840
info@batsound.com


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