Motion Detector (aka Sonic Ranger)

Determine what it does and how it works (without disassembly!).
(You'll need to provide power to the Pasco 750 Interface Box and plug it into your laptop. Insert the yellow plug of the Motion Detector Sonic Ranger into socket 1 of the digital interface and the black plug into socket 2. Run a program called "Science Workshop." You'll have to open an appropriate set-up file from the software.)

Develop a set of specifications for its operation. (What would be the important operating parameters?)