A WiFi sensing system for monitoring a place, the WiFi sensing system comprising a mesh of devices , the mesh comprising : a first set of mesh devices located in the place, wherein each mesh device comprises a transmitter component, which, when activated, configures the mesh device as a transmitter device to transmit wireless signals according to a WiFi protocol and a receiver component which, when activated, configures the mesh device as a receiver device; and at least one active transmitter device which is controllable to transmit wireless signals according to a WiFi communication protocol at a predetermined frequency; the system further comprising a configuration tool which is adapted to form a mesh for a sensing application in the place; wherein the active transmitter device comprises a processor having an operating system configured to implement code to enable the transmission of the active transmitter device to be controlled and to enable communication between the active transmitter device and the configuration tool, wherein the configuration tool implements a mesh forming algorithm at each of the mesh devices , the mesh forming algorithm adapted to execute: (a) an environment sensing phase in which the at least one active transmitter device is controlled to transmit wireless signals at the predetermined frequency , each mesh device configured as a transmitter device is controlled to transmit wireless signals and each mesh device configured as a receiver device is controlled to report to the configuration tool a quality of the wireless signals from one or more candidate transmitter device transmitting the wireless signals, and (b) a mesh forming phase in which n transmitter devices are selected from the candidate transmitter devices from which each mesh device configured as a receiver device receives sensed data when used in the sensing application, the n transmitter devices selected such that the quality of the received signals is suitable for the sensing application . a first set of mesh devices located in the place, wherein each mesh device comprises a transmitter component, which, when activated, configures the mesh device as a transmitter device to transmit wireless signals according to a WiFi protocol and a receiver component which, when activated, configures the mesh device as a receiver device; and at least one active transmitter device which is controllable to transmit wireless signals according to a WiFi communication protocol at a predetermined frequency; the system further comprising a configuration tool which is adapted to form a mesh for a sensing application in the place; wherein the active transmitter device comprises a processor having an operating system configured to implement code to enable the transmission of the active transmitter device to be controlled and to enable communication between the active transmitter device and the configuration tool, (a) an environment sensing phase in which the at least one active transmitter device is controlled to transmit wireless signals at the predetermined frequency , each mesh device configured as a transmitter device is controlled to transmit wireless signals and each mesh device configured as a receiver device is controlled to report to the configuration tool a quality of the wireless signals from one or more candidate transmitter device transmitting the wireless signals, and (b) a mesh forming phase in which n transmitter devices are selected from the candidate transmitter devices from which each mesh device configured as a receiver device receives sensed data when used in the sensing application, the n transmitter devices selected such that the quality of the received signals is suitable for the sensing application . <EOS>