A security monitoring system

A security monitoring system for a building or a secured space within a building, the system being operatively connected to a monitoring station, the system including: a control unit for controlling, arming and disarming the security monitoring system, and having a radio frequency transceiver, and a controller for controlling the radio frequency transceiver; a camera node having: a node controller; an image sensor for capturing images; a node radio frequency transceiver, for communication with the control unit; the node controller being configured to: transmit a captured image as an image file using the node radio frequency transceiver, wherein the transmission of the image file to the control unit is subject to a predetermined maximum transmission duration; and wherein the node controller is further configured to determine the resolution and compression of the image file based on the predetermined maximum transmission duration and an estimate up of the uplink bandwidth between the camera node and the control unit in order to enable the image file to be transmitted to the control unit within the predetermined maximum transmission duration; the control unit being configured: to perform measurement of RSSI and to transmit a measured RSSI value to the camera node; in response to receiving an event notification from a node of the system, to transmit, using the radio frequency transceiver, a control message to the camera node for the camera node to transmit a captured image; the control unit being further configured, on reception of a captured image file from the camera node, to transmit the received image file to the monitoring station.