The device for monitoring a situation within a volume includes at least one electronic unit containing a plurality of different types of sensors, at least one program for controlling the sensors according to a predefined profile and a program for processing data recorded by the sensors, a device for signaling the detection of data representative of an event within the volume, a remote management unit and device for exchanging data between the electronic unit and the remote management unit defined by a radio transmitter/receiver that includes the electronic unit and the remote management unit. The electronic unit includes a device for manual activation of the radio emitter, defined by a button arranged on a housing for an infrared presence sensor equipped with its lens forming a protuberance on the outer face of the unit. The invention also concerns a method for monitoring a situation within the volume by the device.