Abstract: Embodiments relate to a device for mounting on a wall for monitoring an environment. In one embodiment the device comprises: a body comprising: an active reflected wave detector; and a processor coupled to the active reflected wave detector, the processor configured to: control the active reflected wave detector to measure wave reflections from the environment to accrue measured wave reflection data, and identify a status of a person in the environment based on the measured wave reflection data, wherein the processor assumes, for said identification, that the active reflected wave detector is at an operating height above a floor of the environment. The device comprises a cord extending from the body, the cord having a length for ending at the floor when the device is mounted with the active reflected wave detector at said operating height and the cord is freely hanging and straight.