Pop Up Target
Here are several potential principles of operation for such system:
(1) The target is made of paper with horizontal (in one side) and vertical (on the other side) lines made with conductive ink. The lines broken by the bullet were detected and the coordinates of the hit were established. I’ve seen a system that works on this principle.
(2) Optical transmitters and receivers. The bullet interrupts the beams.
(3) The bullet hits a hard target. There are microphones near the target. The sound will arrive to the microphones at different times. The location of the hit is calculated from the time-difference of arrival (TDOA).
(4) Radar?
P.S. I’d like to invite your question to a group dedicated to sensors: **broken link removed**.