Fred No, this unit cannot sense through walls. If you were inside a tent and the person(s) were leaning up against the tent fabric, where you aimed the camera it could possibly show the increase in temperature. Remember this device is optical based IR (Infra Red). Just like a camera cannot "see through walls", this device needs to be able to reflect its IR source out towards the DUT (Device Under Test) and upon receiving or seeing the IR reflection's temperature-altered frequency of light waves, it "builds" a color image based on this. I hope this helps you.