D. E. Zachateysky, B. G. Shadrin

The majority of present multichannel HF communications centres incorporate transmitters with various capacity of radiation, which are used for maintenance of straight lines (without relaying) radio communications. Thus on the reception and transmitting centers such communications centres are used complex enough and large-sized antenna systems. Each of antenna systems is intended for maintenance of communication in one direction and can be used effectively only for some distances. In the paper following basic directions of modernization of communications centres are offered: Replacement of becoming outdated lamp transmitters by modern transistor transmitting modules with power no more than 1 kW each with digital activators in the structure, capable to provide synchronous work of several modules for maintenance of necessary quality of message transfer in complex conditions. Replacement of bulky receiving antenna systems by modern antenna systems with controlled position of the directional diagram. Effective forecasting (diagnostics) of conditions ionospheric radiowaves propagation, allowing to organize adaptation of operating modes of a communication facility to changing (dynamic) parameters of radiolines. Realization of the first direction of optimization will allow unifying radio transmitters and improving service. Replacement of antenna systems will allow reducing the areas occupied by antenna fields. Offered modernization does not demand big expenses for capital construction (antennas can be placed on the ground or on roofs of buildings). Operational service of new antennas does not demand steeplejack works. The modular principle of construction of phased-array radar assumes an opportunity concerning simple replacement of separate elements of an array antenna and carrying out of the basic part of repair work in a room instead of field condition. The third direction is determined by a modern computer aids allowing operatively solve problems of modeling and computer support of decision-making. In the paper the authors estimate necessary radiating power of transmitters in multichannel HF communications centres for maintenance of reliable information interchange with similar centres using methods of computer modeling under conditions of using phased-array radars and accommodation of communications centres within Russian Federation. The authors also analyse the opportunity of use of number of transmitting modules in radiocommunication center designing is analyzed. Transmitting modules have no more than 1 kw. each radiating power and permit messaging in 7000 km-distance radio links. It is shown, that for the considered conditions offered directions of modernization are practically sold. Receiving arrays will allow to use for the majority of radiolines transmitters with such power. The radio communication in other cases can be carried out by summation of power of several modules or relaying.