Abstract: A base station transmits a synchronizing signal and a clock and AGC circuits of numerous sub-stations produce AGC voltages for indicating adjustment of gain and adjust levels of received signals converted to an intermediate frequency supplied from a frequency conversion unit on the basis of the AGC voltage so that the levels of the received signals are maintained constant in order that the base station can collect a small amount of data from each of the sub-stations in an extremely short time. A data processing circuit of each sub-station transmits data to the base station at a transmission timing corresponding to an identification number of its own sub-station on the basis of the synchronizing signal and the clock in the received data and a gain control circuit adjusts transmission power on the basis of the AGC voltage.

Abstract: The present invention provides a screen plate cleaning station having nozzles for discharging a cleaning liquid to clean a screen plate which has been set in place, the station comprising a hood-like cleaning zone setting means which are provided on both sides of the screen plate in such a manner that their extremities are in contact with the both surfaces of the screen plate, thereby defining substantially equal cleaning zones on the both sides to prevent the cleaning liquid discharged from the nozzles from scattering.