Tower Microphone TM20 for BATmode systems

The electret ultrasonic tower microphone TM20 was specially designed for mounting in the tower wall of large wind turbines for the qualitative detection of bat activity at the level of the lower rotor tips. While the focus of the tower microphone TM10 was on having the smallest possible diameter, the TM20 includes a 40kHz test signal speaker in addition to the microphone. As for the microphone discs for nacelles, this speaker is used to play a daily 40kHz test tone for checking and logging the microphone sensitivity during a continuous long-term monitoring. With a microphone diameter of only 20mm, the required diameter of the mounting hole of 22mm is still extremely small. For mounting in the tower wall, the optional TM20 - Mounting-Kit is available. The tripod of the Mounting-Kit slides along a rod, which is fixed to the microphone. Thus, the microphone can be easily fixed in tower walls with different wall thicknesses up to 450mm and allows a defined positioning of the microphone tip. The tripod is mounted on the tower inner wall using either magnetic feet, adhesive pads or screws (see the Drilling Plan - TM20 in Product Attachment). To prevent the ingress of rainwater through the mounting hole it can be drilled slightly sloping into the tower wall. To further increase the reliability of the microphone in adverse weather conditions, the TM20 integrates a microphone heater, which reduces condensation on the microphone. Due to the M3 mounting bolt on the back of the microphone, the microphone is also ideal for alternative measuring situations, such as on measuring masts, in addition to the use in the tower of wind turbines. Like all other microphones, the TM20 is compatible with BATmode 2S and BATmode 2S+ as well as the UltraSoundGate 116Hnbm and 416Hnbm from Avisoft Bioacoustics.

Note : To reduce electromagnetic interferences, we recommend to place the BATbox with the detection system as close as possible to the microphone hole and as far away as possible from interference sources such as power and control cables. For this the microphone is delivered with a 3m connection cable. In principle, it is also possible to install the BATbox on the tower base and to use an extended microphone cable. However, this may cause a significant reduction in recording quality.

Main features

• Knowles FG - Microphone capsule
• 40kHz test signal speaker
• Integrated microphone heating
• ∅ 20mm / Length 55mm
• M3 mounting bolt
• Tower wall mounting with TM20 - Mounting Kit available separately