We have made a lot of advances on the detector side of things so decided to re-visit the use of the quad-copter, something we had moved away from due to issues with motor noise and the weight of the detector.
We suspended the Peersonic detector under the quad and flew a small route of approximately 200 meters along tree-lines surrounding a field. In the corner of the field we picked up bats. This is the first time we have picked up high quality recordings of bats using our setup!
The flight path of the quad-copter
Sonogram of our first recordings
Video of the flight with audio from a Bat Box Duet (held at ground level along with the camera)
This is a real break though as the noise we see from the propellers is clearly significantly quieter that the calls we recorded. To reduce this further we hung the detector a little lower (initially 2m and changed to 4m) from the quad and got some even better calls from Common Pipistrelles (Pipistrellus pipistrellus). We know these are common pipistrelles because of their 'hockey stick' shape and because the peak frequency is at around 45kHz.
We are going to continue to explore the potential of both the quad and the fixed wing as platforms for bat detectors.
Watch this space!