Frequently Asked Questions

The "Tape" output of the D100/D200/D230/240x bat detector has a two-channel (stereo) jack. In order to use a mono recorder, you need a special "stereo-to-mono" cable that connects the channel from which you want to record to a mono (2-pole) plug that fits in the recorder.

The D940/980 uses "phono" jacks on the Tape output, hence a mono cable is all it takes to connect it to a mono recorder.

If you have a stereo recorder, you should use a two-channel (stereo) cable. The D500X and D1000X have built-in recorders so there is no need to connect an external recorder.

Answer: Yes. The easiest way is to make an “adapter” that fits on the regular 9 V battery connector of the detector and connect the external battery through the adapter. The “adapter” can be made of a standard 9 V battery connector with leads:

The external battery is connected to the leads of this connector with the positive terminal to the black lead and the negative terminal to the red lead. Please note that this is opposite to the common standard and this is because the battery connector is used in the opposite direction in this case (to supply current rather than to receive). Before connecting an external battery to the detector using the above adapter, you should carefully verify that the polarity at the battery connector is the same as that of a 9 V battery, e.g. using a multimeter. Reversing the polarity may cause permanent damage to the detector.

Most standard accessories can be used with Pettersson bat detectors. As long as you follow the recommendations given in the Operating Instructions of the bat detector, you can equally well purchase accessories in your local electronics store.

Unattended recording of bat calls has become a widely used method to monitor bat activity. The advantage is obvious – several recording units can be administered by one person, which gives a very cost-effective solution. The D240X is a bat detector which is suitable both for traditional, manual monitoring and unattended monitoring. In the automatic triggering mode, the D240X captures the bat calls as they are detected and then plays them back at slower speed.

The Zoom H2 is a high-quality digital recorder, using an SD card as storage medium. It is the perfect companion for the D240X both for manual and automatic recording. In the "voice activated" mode it starts recording as soon as the D240X starts playing the bat call, enabling a fully automatic, unattended recording session.

The two units are connected with a 3.5mm plug stereo cord from the TAPE jack of the D240X to the LINE IN jack of the Zoom H2.

Recommended settings:


GAIN switch: HIGH
TRIG switch: AUTO

Other switches can be set as desired (please refer to the D240X Operating Instructions for more information).

Zoom H2

REC MODE: WAV 44.1 kHz/16 bit
STOP LVL: -40 dB
AUTO STOP: 1 sec
REC LEVEL: 90 (left/right arrow keys)

Other settings as desired.

To start a recording session, switch on both the D240X and Zoom H2 and press the red Recording button on the Zoom H2 once. The text "Wait for signal..." is displayed. Make a sound, e.g. by snapping two fingers, to trigger the D240X and verify that the Zoom H2 starts recording the signal. To end the recording session, press the PLAY/PAUSE key of the Zoom H2 and turn off both devices.

The recorded files will have the time expanded signal on the right channel and the heterodyne signal on the left channel.

The instructions above are for Zoom H2 firmware version 1.8.

No, heterodyne signals are not well suited for analysis. The main reason for this is that the frequency of the output signal from a heterodyne detector depends on the setting of the frequency control (the tuned frequency), so it will vary depending on the setting.

A "high frequency" output gives the original, unaltered signal. Such an output is used to record the high frequency sound on a device capable of recording high frequencies (a computer with high-speed sound card or a high-speed recorder). The D200 detector has a high frequency output available all the time, while the other D2xx detectors don't. However, pushing the Comment button will feed the original, high frequency signal from the microphone to one of the two output channels on the D230/240x detector. So, as long as you push this button, you have the high frequency signal available for recording.

The D500X has a small back-up battery built in, which keeps the real-time clock running when the detector is not run from its regular batteries. If the D500X loses the time and date, the back-up battery is empty and should be replaced. The way this is done, depends on the version of the D500X. Early units require that the unit is disassembled while on more recent units, the back-up battery can be accessed after removing only the front panel (the one with the CF card slots). Please contact Pettersson Elektronik for more information about this.

A temporary solution is to avoid turning the D500X off with the INT/EXT power switch (use the 1/0 switch on the keyboard instead). Then the real-time clock will be powered from the main batteries instead.

D500X version 1 firmware required the CF cards to be formatted and then "prepared" with the D500X Utility program. The preparation step has been eliminated in version 2 firmware, so from version 2 and on, the CF cards should only be formatted in Windows (as FAT32), not "prepared". Consequently, the preparation command has been removed from the current version of the D500X Utility program.

The battery indicator shows the battery voltage, not the remaining battery life time. Especially if an external battery with a higher nominal voltage is used, the battery voltage may be high enough to make all segments of the battery indicator turn on even if the battery is far from fully charged. Checking the condition of external batteries with a battery tester will provide a better indication of the battery status.

The current D500X firmware version shows the actual voltage in Volt, rather than a bar indicator. This gives a better measure of the battery condition.

Time Expansion (TE) and Frequency Division (FD) detectors are both "broadband" detectors. This means they will make the entire ultrasonic range audible all the time (in contrast to a Heterodyne detector, which is sensitive only to a limited range of frequencies at each time). There are, however, several important differences between the two types.

A FD detector transforms the ultrasonic calls in real time, i.e. the calls are heard through the detector at the same time they were emitted by the bat. A TE detector first stores a portion of the ultrasonic signal in its digital memory and then replays it at a slower speed, i.e. it is does not transform the calls in real time. The delay depends on the actual storage time, and if this is very short (up to around 100 msec), the replay is also made fairly quickly and the detector gives an "almost real time" response.

Since the TE detector actually stores the original signal (which is then stretched out in time), the output of such a detector provides the same information as the original signal. Hence, it is possible to make any type of analysis and obtain useful and accurate results. This includes spectral analysis of all types (e.g. spectrogram/sonagram). A FD detector counts the number of cycles of the ultrasonic signal and generates an output cycle (pulse) for each N input cycles, where N is often 10. This effectively divides the frequency by N. Obviously, an FD detector is only capable of tracking one frequency (harmonic) at each time. Usually (but not always!), this is the fundamental frequency. Consequently, it is not possible to perform any harmonic analysis from an FD signal. To do this, TE signals should be used.

TE detectors have a number of other advantages over FD detectors. For instance, the former are more sensitive and offer the user better possibilities to aurally analyze the transformed calls.

To conclude, if you require a broadband bat detector, a TE detector is usually the best choice. However, if the limited storage time of the TE detector is a problem and/or you need a real time response, a FD detector should be chosen. As an alternative to a TE detector, direct high-speed recording of the ultrasonic calls can also be made with the D500X and D1000X detectors. In that case there is virtually no limit on the recording length (storage time).