Abstract: A manhole monitoring unit includes a housing mountable to walls of a closed manhole, without breaching an insulating layer on the walls, a data processor to receive data from monitoring sensors in the manhole, and a communication unit at least for transmitting wirelessly the data to an external network unit located above ground. A manhole monitoring and control unit includes a housing mountable to walls of a closed sewage manhole, without breaching the walls, a data processor to receive data from monitoring sensors in the manhole and to control actuators according to high level network commands, and a communication unit for transmitting wirelessly the data to an external network unit located above ground and receiving commands.

Abstract: A portable receiving/transmitting unit is adapted to communicate with a master station, the master station being associated with a plurality of base stations, a plurality of pagers and a plurality of individual receiving/transmitting units. The portable receiving/transmitting unit includes, integrated into one unit, structure for receiving a data string encoding a personal message which is broadcasted by the master station together with a unit identifying code through a plurality of pagers; structure for conveying the broadcasted message to the operator of the receiving unit identified by the identifying code; and structure for generating a message and for transmitting it from the portable unit to the receiving base stations together with a unit identifying code.