FIELD : radio engineering.SUBSTANCE : invention is intended for exchange of messages between secured objects (SO) - transport vehicles and real estate objects - and centralised security station (CSS). In SO they generate and send to CSS alarm or control messages, moreover, alarm message is generated after alarming event occurs in SO, and control message - on completion of established time gap after the last transfer of message to these SOs. Using received messages, in CSS they establish necessity to send command message for appropriate SO, it is sent to this SO and there received command message is executed. In structure of sent messages they separate synchronising marker, information block and control sum. For CSS and SO they preliminarily establish duration of each message digit transmission, and also maximum and minimum permissible frequencies of transmission. When messages are received in CSS, they identify frequency of received message and phase linkage of its digits, and also code of information block, they calculate control sum and compare it to control sum in received message. In case they coincide, they assume the message is received, and adequate reaction is generated. In CSS they generate command message directly on completion of message reception from SO and it is sent to SO on frequency that corresponds to frequency of alarm signal or control message, which is established during reception of message signal, as cophased to its digits. In SO on completion of message transfer they memorise frequency and phase of transmitted message an wait for reception of command message from CSS during established time gap on memorised frequency and phase.EFFECT : high noise immunity and large permissible distance between SO and CSS.6 cl, 3 dwg