Trailer Heartbeat — Stowaway & Intrusion Sensing

WiFi threads through cargo stacks and thin walls where no camera can look. A concealed person, even lying perfectly still, breathes — and that slow rhythm marks the signal. A break-in at rest is even louder: a sharp jolt plus a lasting change in the echo pattern of the doors.

In the physics: RF penetrates cargo stacks and thin walls; a concealed human adds a breathing-band micro-Doppler signature and perturbs multipath amplitudes even when motionless. Door breach and human entry create large transient Doppler plus a step change in CIR path structure.