After reading about military Ground Surveillance Radar that had a Doppler (Wiki) output and how just be the sound you can tell what's making it by instinct. This is exactly how I feel about the PSR-1 seismic outdoor intrusion sensor where when the infrasonic energy is upconverted to sound, when you hear it you know what is making the infrasound. I'd like to get one of the Ground Surveillance Radars like the AN/PPS-4 or AN/PPS-15, but they are hard to find and expensive.
The next best thing may be to get a Doppler Radar module but a RADAR Gun was recommended because it has much more range. So got the Bushnell Velocity RADAR gun. Note I know it does not have an audio output, but I think one can be added. Here's a web page showing inside photos.
Teardown Tuesday: Radar Gun -
While the first genertion radar speed guns (Wiki) worked at 10.525 GHz. This model works at 24 GHz (Wiki: K band). This is one of the Industrial Scientific Medical bands (Wiki) that can be used, with some minor limitations, without a specific license.
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