Pettersson D230

Available, usually ships in 1-2 business days

The Pettersson D230 is a combination  heterodyne (HET) and frequency division (FD) detector for real-time active monitoring. Using stereo headphones, you can constantly monitor the bat's full frequency range in FD in your right ear. The HET output is also constantly being played in your left ear. When a bat arrives, quickly tune the HET into the strongest signal. The frequency on the display will be where the bat's is calling the loudest, and is a huge step towards identification. In fact, with some context as to where you are recording and what species are expected in the area, it is possible to narrow down the possible candidates. 

This quality bat detector features a large, accurate, backlit digital LCD displaying the center of the tuned frequency in kHz. The HET detector in real time plays any ultrasound that is approximately 4 kHz above and below the tuned frequency. This method works by frequency subtraction and only a very narrow part of the spectrum is scanned at any given time.  When headphones are not used, a switch allows you to listen to either HET or FD via a speaker.

Frequency Division is full spectrum recording but with much less resolution. It contains amplitude and multiple frequency content but only the fraction of the temporal resolution, making it unusable for professional level analysis. However, it can display low-res spectragrams in real time, and can give a more complete picture than heterodyne-only devices.The FD signal can be played into a computer or smart device to display a real-time sonogram. FD devices produce low quality analog output that is not used for precision computer analysis. However, many people are able to discern different species with practice in areas where there is little overlap in call frequencies, and quiet environments.

With practice and becoming familiar with bats in your area, you will be able to group calls by genus. This is great for interpreters doing bat walks, or bat enthusiasts looking for a low cost acoustic detector. Tone qualities of the output change if the bat is calling above or below the present frequency of the detector. This enables users listening in real time to rapidly "tune into" the bat as it flies by and get a good estimate of the bat's dominant frequency, the basis for species identification.

Please note: heterodyne detectors -are not- intended for ultra precise computer analysis and species identification for agency compliance surveys. They can be used for other applications, such as passage rates at mine or cave entrances, monitoring roosts, etc.