USG Electret Ultrasound Microphone with Test Signal Speaker mounted on a 90 mm Disk
Avisoft Bioacoustics / Knowles FG-DT90
part #40009
The Avisoft Bioacoustics 90 mm disk microphone is intended for installation at the bottom of a wind turbine nacelle. It is equipped with a 40 kHz test signal speaker and a microphone heating for improving the reliability under adverse weather conditions. This setup has been desiged in cooperation with the German BMU-funded research project on reducing bat fatalities at wind turbines in central Europe.


- Approximate input-referred self-noise level (bandwidth: 30-50 kHz): 26 dB SPL
- Approximate sensitivity: 500mV/Pa
- Power supply : 5V, 25 mA (provided by UltraSoundGate x16Hnbm)
- Microphone connector: male XLR-5 plug
- Test signal speaker connector: male XLR-4 plug
- Heating conncetor: USB B connector
- Included cables: 1 x Microphone and speaker control cable (5m) for the connection to the UltraSoundGate 116Hnbm/416Hnbm base unit, 1 x USB power supply cable (5m) for the heating (note that this microphone model requires the USG 116Hnbm or 416Hnbm – other models are not directly compatible).
- Disk diameter : 90 mm
- Mounting disk diamter: 140 mm
- Recommended drill diameter on the nacelle: 100 or 102 mm
- Depth : 45 mm
- Weight : 250 g

frequency response

Principe of the complete Wind Turbine Bat Monitoring System according to the BMU-funded research project (click to enlarge)

polar diagram