Wall-Breach Early Warning: Drill & Cut Detection

Drilling makes the wall itself vibrate, and a vibrating wall shakes the WiFi signals reflecting off it — that is the first warning. Removing wall material then permanently changes how signals pass through that spot, so the breach leaves a lasting scar in the field even if the drilling stops.

In the physics: Two independent observables: (1) percussion/rotary drilling couples low-frequency structural vibration (1-40Hz envelope and harmonics) into walls, phase-modulating paths that reflect off the vibrating surface; (2) removing wall material locally changes eps_r and thickness, producing a persistent CIR delay/amplitude change on paths through that wall section — a breach leaves a scar in the field even if the tool is silent.