FIELD: signal generating devices for random-access broadcasting systems. SUBSTANCE: device for periodic generation of set of messages has means for generating plurality of messages, random-access means for periodic random access to sequence of messages including generation of plurality of sets of such messages randomly disposed in each set, and means for outputting mentioned plurality of sets of messages. Access control system for broadcasting and receiving system has on broadcast end of said device for periodic generation of set of messages and on receiving end, device for receiving mentioned messages. Broadcasting method includes stages of data broadcasting, generation of control command characterizing some attributes of mentioned data, and periodic broadcasting of some message at varying repetition frequency that changes in response to mentioned control command. EFFECT: reduced requirement to system capacity. 60 cl, 20 dwg
