Frequently asked questions about Pettersson Bat Detectors
Question.
Pettersson Elektronik sells various accessories such as cables, headphones and batteries. Do I have to purchase such items from Pettersson Elektronik or can I use other types?
Answer.
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.
Question.
Is there a "High Frequency" output on the D230/240x bat detector?
Answer.
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 tape 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.
Question.
Can I use a monophonic tape recorder to record from my bat detector?
Answer.
The "Tape" output of the D100/D200/D230/240x bat detector has a two-channel (stereophonic) jack. In order to use a monophonic tape recorder, you need a special "stereo-to-mono" cable that connects the channel you want to record from to a mono (2-pole) plug that fits in the tape recorder.
The D940/980 uses "phono" jacks on the Tape output, hence a mono cable is all it takes to connect it to a monophonic tape recorder.
If you have a stereophonic tape recorder, you should use a two-channel (stereophonic) cable.
Question.
What are the differences between Time Expansion and Frequency Division bat detectors?
Answer.
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.
An 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 that of 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). An 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, an 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 a laptop computer and Pettersson Elektronik's program BatSound Pro. In that case there is virtually no limit on the recording length (storage time).