Using ITU-R 370 Method to Analyse Spread (Propagation) Conditions in Land Mobile Systems

Summary form only given. The main property characterizing of all telecommunications systems is its utilization for electromagnetic space. This space is defined as component of the following elements: electromagnetic spectrum, physical space and time. In deed each microwave instrument presents a point in electromagnetic space, while it´s taken in consideration operating frequency, its coordinates and operating time. Interference of two equipments occurs when the distance between the bodes which present them in the electromagnetic space is not big enough. During the development of telecommunication systems there has been inserted a big number of equipments and communications systems into the electromagnetic space which is surrounding the earth. These equipments and systems clearly effect the state of electromagnetic space. Previous existing systems caused passive effect to the new one and at the same time it also affects the old systems. The source of the spectrum and electromagnetic space are natural sources for all human beings, therefore we should protect it and use it in an ideal way. From this point of view we have to note that in a geographical area we can´t built unlimited number of telecommunications systems , therefore we must find technical solutions , design methods and operations conditions to ensure permanent working of all equipments fixed in those systems, especially in case to improve and integrate existent communications net and to plan new ones. The ITU-R370 method (previous CCIR 370) is considered as one of the best methods used to calculate waves spread in telecommunication systems working in metric and dissymmetric wave frame. This method enables analyses and calculations concerned for common use of spectrum and studying and evaluation possibilities of interferences inside the system and between the communications systems working in the same space and also makes possible determination enough distance between two stations operating by the same fr- - equency on the bases of the same information depending on geographical variation of different area, structure path and spread conditions of electromagnetic waves in used frequency limits. In addition ITU-R370 method is used according to international contracts to organize the communications systems working in metric and dissymmetric wave space on international boundaries sections. The aim of this work is to study the effect of the following parameters on the determination intensity precision of desirable and undesirable fields. The chosen parameters are Deltah as parameter to evaluate effect of terrain roughness on microwave path, thetas as a parameter to evaluate effect of terrain roughness on signal receiving area and h_eff as a parameter to evaluate effect of terrain roughness around antenna. According to this study it concludes that the mentioned method can be used to analyse spread conditions in mobile systems after taking in account some modifications resulting from the effects of the above mentioned parameters