This paper introduces analyzes of the Frequency Division Multiple Access (FDMA) applicable in Global Mobile Satellite Communications (GMSC). In satellite systems, as a rule, especially in GMSC many users are active at the same time. The problem of simultaneous communications between many single or multipoint mobile satellite users, however, can be solved by using the Multiple Access Technique (MAT) scheme. Since the resources of the systems such as the transmitting power and the bandwidth are

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... mited, it is advisable to use the channels with a complete charge and to create different MAT schemes to the channel. This generates a problem of summation and separation of signals in the transmission and reception parts, respectively. Deciding this problem consists in the development of orthogonal channels of transmission in order to divide signals from various users unambiguously on the reception part.