Gregory “Mr. Vacuum Tube” Charvat (whose work was featured on the blog several times) breaks down an old school police radar:

It is amazing what additional information can be gained by modifying old equipment.

Here we connect the video output of an old police radar gun to the audio input of a laptop and applying basic signal processing techniques display doppler vs. time spectral plots of various targets.

Doppler signatures of birds, someone running, and cars are observed. Also relative radar cross sections of these targets are noticeable (cars are brighter than birds).