An apparatus for detecting an object in an environment, the apparatus comprising: a processor, the processor coupled to an active reflected wave detector that is operable to measure wave reflections from the environment, wherein the processor is configured to: process measured wave reflection data to determine whether a predetermined condition is met, wherein the predetermined condition comprises that an object is located in, or has moved towards, a predetermined area within a field of view of the active reflected wave detector; the measured wave reflection data accrued by the processor in response to the active reflected wave detector being activated in response to a motion sensor detecting motion in said environment; and if the predetermined condition is met, perform at least one operation related to camera image data representing a captured image of the environment, the camera image data being: captured by a camera in response to the motion sensor detecting motion in said environment; or captured by the camera in response to the predetermined condition being met; and a housing holding the processor, the motion sensor, the active reflected wave detector, and the camera. a processor, the processor coupled to an active reflected wave detector that is operable to measure wave reflections from the environment, wherein the processor is configured to: process measured wave reflection data to determine whether a predetermined condition is met, wherein the predetermined condition comprises that an object is located in, or has moved towards, a predetermined area within a field of view of the active reflected wave detector; the measured wave reflection data accrued by the processor in response to the active reflected wave detector being activated in response to a motion sensor detecting motion in said environment; and if the predetermined condition is met, perform at least one operation related to camera image data representing a captured image of the environment, the camera image data being: captured by a camera in response to the motion sensor detecting motion in said environment; or captured by the camera in response to the predetermined condition being met; and process measured wave reflection data to determine whether a predetermined condition is met, wherein the predetermined condition comprises that an object is located in, or has moved towards, a predetermined area within a field of view of the active reflected wave detector; the measured wave reflection data accrued by the processor in response to the active reflected wave detector being activated in response to a motion sensor detecting motion in said environment; and if the predetermined condition is met, perform at least one operation related to camera image data representing a captured image of the environment, the camera image data being: captured by a camera in response to the motion sensor detecting motion in said environment; or captured by the camera in response to the predetermined condition being met; and captured by a camera in response to the motion sensor detecting motion in said environment; or captured by the camera in response to the predetermined condition being met; and a housing holding the processor, the motion sensor, the active reflected wave detector, and the camera.