Ganzha S. Improvement of quality of broadcasting in the synchronous network of VHF-FM of transmitters.

Object of researches is the system of VHF-FM synchronous broadcasting. Subject of researches are distortions, arising at sta-tionary and mobile reception of radio signals in VHF-FM synchronous broadcasting network. Research methods: the mathematical analy-sis, the mathematical statistics, formulation and carrying out of experiment, modelling on computers. Scientific novelty of the received re-sults: research of linear, nonlinear and transitive distortions which allow to establish necessary values of protective relations; it is estab-lished, that in case of mobile car reception the distortions have oscillating character; for the first time it is established, that in the mobile car the radio reception distortions averaging occurs on the sections of the territory equal to the wave length, contributing to improve the reception quality; for the first time parameters “effective“ frequency response irregularity and “effective“ harmonic factor are used which allow to establish an integrated distortions estimation; on the basis of the new developed method in field conditions measurements the ex-tent of distortion zone of VHF-FM broadcasting in the interval between two synchronous transmitters and the new way of its minimiza-tion which allows to improve quality of broadcasting on a considerable part of territory is developed; at carrying out of subjective-statistical examinations of the soundings fixed at radio reception on the territory between synchronous transmitters, the parameters of a synchronous network necessary for its planning were defined. The basic theoretical conclusions of dissertational job were confirmed by RSW (research scientific work) performance in the Ukrainian Scientific Research Institute of Radio and TV, in the Odessa National Academy of Telecommunication named after A.S. Popov by preparation of the patent for the invention „The definition way of a path link of synchronous broadcasting with the increased nonlinear distortions” by contribution preparation in ITU-R ”the Offered definition method of a zone of nonlinear distortions at radio reception in VHF-FM transmitters of synchronous broadcasting network”, which can be confirmed by the introduction certificates. Main results and conclusions of the thesis are as follows: to build a network of synchronous VHF-FM transmitters which provide radio reception in stationary conditions and auto vehicle (car) which moves along the highway, it was necessary to obtain data on possible distortions during radio reception of voice programs and necessary protective relations which provide improvement of radio reception quality; theoretical researches of distortions which occur during radio reception in synchronous networks VHF-FM transmitters helped to obtain preliminary estimates of protective relationships and establish that these distortions have oscillating character during radio reception in moving car. This conclusion allows us to establish that in this case the distortion can be averaged, and therefore it improves the quality of mobile radio reception; new method of measuring nonlinear distortion in radio reception in synchronous transmission network is proposed, that allows to define zone of nonlinear distortions on the territory between the transmit-ters. In process of conducting of field tests conclusions were obtained which confirm theoretical researches of periodicity of change of nonlinear distortions on the lengths equal to the wavelength, and therefore the nature of the change of nonlinear distortions in moving car has oscillating character; in the process of subjective-statistical examinations of voice transmissions quality which were recorded at vari-ous points on the territory between synchronous transmitters in the field tests refined values of protective relations were obtained. It was established that the required values of protective relations are defined depending on the width of spectrum of transfer’s fragments, these values are higher for classical music. The results of theoretical researches and experiments conducted during the field tests, gave the pos-sibility to complete calculation and implementation of synchronous transmission network, which consists of four transmitters operating at frequency of 107.7 MHz; system of synchronization and carrier frequency modulation is developed, customizing of synchronous transmit-ters system was made to obtain minimal extent of distortion zone.