I have made some recordings two nights ago with two Audio Moths setup as static recorders and a mobile handheld Petterson M500-384 for comparison. The AudioMoths were placed at ground level, angled about 45 degrees upwards and had a 3micron aluminised Mylar film over the microphone for protection (normally used for ultrasonic microphone diaphragms). The two recordings include examples of Common and Soprano Pipistrelles, Noctule, Leislers, Daubentons and a possible Serotine. The Moth was run on the lowest gain setting at 384ksps and the results are very comparable with the Petterson. In particular high frequencies such as the top of the Daubenton's pulses are still clearly visible and apparently not attenuated by the protective film. Files can be downloaded from https://figshare.com/s/f116dc1588e1946415c0f including a screenshot of a single pass from the AudioMoth and from the M500-384 although the microphones were several feet apart and possibly not pointing in quite the same direction which may account for some of the differences, but onn the whole quite comparable.

Thanks Justin, and I expect lots of others will find this helpful - Phil

Having said that, the link doesn't work in Chrome or IE - I get :-

Page not found, but at least you tried.

Or like Wernher von Braun said ...

“Research is what I'm doing when I don't know what I'm doing”

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sorry about that, try https://figshare.com/s/f116dc1588e1946415c0 which works for me in Edge

Yes that worked thanks, I can display the traces with SpectraVue nicely. This is 23Khz to 96Khz. Theres a burble running at 52Khz that could be a street light or something.

I have added two additional files, CHC18-1am2_20180406_203154.wav and CHC18-1p_20180406_203333.wav which are overlapping recordings made with the AudioMoth and a Petterson M500-384 using Bat Recorder - the AudioMoth at ground level angled up and the Petterson handheld. Comparing the recordings in detail the am recordings appear to have a better s/n ratio and pulses extend to higher frequencies. However on closer examination the Petterson pulses are much cleaner and the am pulses include a number of intermodulation distortion components which makes me think that the higher harmonics in these recordings are actually artefacts. In short the number of pulses caught by each system is pretty much the same and for identification purposes the am recordings are fine, but if you are more interested in looking at the detailed structure of pulses or making accurate measurements of duration/bandwidth/harmonic content, then there some issues with the audio moth which would need to be carefully resolved first. Probably be replacing the microphone with a signal generator and making accurate maps of frequency response, distortion and intermodulation, however I unfortunately no longer have the facilities to do this. And as I said earlier, for identification purposes these issues are not a problem.

here are some audiomoth recordings from my garden https://drive.google.com/open?id=1MezOhpzuOFGGxeX4Rd2pkucu30SeLNiv

Thanks for sharing these recordings guys. Really useful.