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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

2024 Bat sonograms (1 Viewer)

That looks like Audacity… can you elaborate how you are recording and ID’ing?
I use an ultrasonic microphone ( dodotronic 384evo) connected to android phones/tablets.
There is an app called bat recorder which is excellent, and records every bat that triggers the software.

Other people use the echometers which have their own android app, and can auto identify to some degree.

I move the files onto a windows pc for analysis, and that's the end result, in Audacity for a visual look at the spectrogram.
The microphone is the main expense ~£200-300.

I believe the microphone can run directly into audacity, but I've never got it to work. It would be pretty cumbersome anyway, as you'd have to do a lot of work to get the triggering and frequency division of the signal to make it audible etc. the bat recorder app does all that pretty seamlessly.
The microphones also seem a bit hit and miss. Don't work on every Android device.

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ID'ing UK bats, about 12 of our species are relatively straightforward to identify just by the echolocation sonogram.
A couple more doable at a push.
Then the remainder are in the Myotis group, and their calls are all pretty much straight lines with very little to differentiate.

The Auto Id programs out there (Batdetect for UK species) seem reasonably ok. I noticed the Barbastelle call as it passed by last night, the BatDetect program picked it out later on the PC.
Never really considered doing this before, but simple noise reduction on the bat spectrogram, in Audacity, gives a much more accurate reading of the start and finish frequency.
For the Barbastelle it would read:
FStart 48.5KHz, FEnd 29KHz, fmax 42KHz, which is what you would expect. (FStart slightly high)

Original on Left, noise reduction on Right:

Not sure about the shading behind the calls, possibly due to a busy environment. I was parked alongside, and pointing towards a hedge. However, this isn't going to affect the readings

Screenshot 2024-02-23 161425.png
By far the most regular bat to get picked up with a bat detector in most parts of UK, Common Pipistrelle.
Hockey stick shaped calls, with a peak at 46KHz in a cluttered environment such as this example. Peak frequency can be as low as 40KHz over open ground.
typically 10 calls per second.

Screenshot 2024-02-23 202912.png

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