Abstract: The invention relates to electrical network communications engineering and can be used in systems for automatic data collection from electric, heat, water, gas meters etc. The technical result is significant simplification of the interior structure of slave units increased noise stability of a system. This result is achieved by using zero crossing points of the fundamental harmonic of system supply line voltage as character synchronization events.

Abstract: The invention relates to electrical network communications engineering and can be used for automatic data acquisition from intrusion and fire-alarm sensors, electric meters, heat, water and gas consumption meters and from the fiscal memory of cash control monitors. Said invention makes it possible to substentially reduce the energy consumption by the slave nodes of a system and/or increase the range of action thereof. In order to encode each symbol of transmitted data, a random or pseudorandom set of differences of initial pairs of nearest harmonic pairs are used. Said difference sets of the initial phases are selected in such a way that the peak factor of an added signal is minimised. When a fire-alarm sensor is actuated, it is sufficient to transmit only one symbol to an alarm panel which, unambiguously identifies the location of the active sensor and as a rule is embodied in the form of a conventional number or address pre-allocated to said sensor.