D240X Ultrasound Detector

Very popular heterodyne and time expansion detector with backlit, large digit, accurate digital display, showing the tuned frequency in the heterodyne mode. The frequency and volume controls are on the side of the case, making it easy to adjust. Using stereo headphones, the heterodyne signal is heard on the left channel and the time expansion signal on the right channel. When the built-in speaker is used, a switch is used to select the heterodyne or time expansion signal.

A digital recorder can be connected to the D240X to record the time expanded calls for analysis on a PC. If the recorder has a "voice activated" recording mode, a fully automatic bat recording system is obtained, which can be left in the field for unattended recording of bat calls.

D240X Ultrasound DetectorD240X Bat DetectorD240X Bat DetectorD240X Bat DetectorD240X Bat Detector


"Not sure you know this but I have been running a D240x 24/7 going on 16 months as part of a year-round study of bats in western Washington. The detector is wired to AC power and an old laptop computer, and enclosed in a PVC pipe with the microphone pointing to an open hole. The end of the detector pretty much exposed to the weather. It has suffered rain, wind, freezing winter cold, high summer heat, and both wasp and spider nests, yet keeps right on working.

I am impressed."

– Gregory A. Green, Bothell, WA, USA


Type: Heterodyne and time expansion (x10 or x20 - selectable via switch)
Microphone: Advanced electret
Frequency range: 10 - 120 kHz (min.)
Display accuracy: ±0.15 kHz (min.)
Bandwidth: 8 kHz (± 4 kHz), -6 dB
Battery: 1 x IEC 6LF22 (9 V)
Quiescent current: 30 mA typ. (replay) including LCD backlight
Comment switch: Yes
Memory size: 1M x 8
Sampling frequency: 307 kHz
Resolution: 8 bits
Storage time: 3.4, 1.7 or 0.1 sec. (selectable via switch)
Trigger modes: Manual, level - broadband, level - narrowband
Pretrigger: 50% of the selected storage time
Size: 119 x 60 x 25 mm including knobs
Weight: 170 g including battery
Outputs: 2 x 3.5 mm jacks for headphones and tape recorder
Miscellaneous: Overload indicator, adjustable input gain, replay of signal in memory through heterodyne system