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  • Synchronization in Direct Sequence Spread Spectrum Systems

    The article conentrates on the problem of synchronization the pseudo-noise sequence in direct sequence spread spectrum systems. Authors propose a method for transmitting information and synchronizing signals on a single carrier frequency, which allows data transmission in complex coditions in radio channel. A brief review of existing solutions for time synchronization direct sequence spread spectrum systems is carried out. The proposed solution is considered in terms of data transmission in broadband systems in the conditions of negative signal-to-noise ratio, while the limitations of the usage of this solution are also considered. A simulation of the scheme that implements the proposed synchronization method is carried out, and the requirements for the signal-to-noise ratio in the information and synchronization channels are determined. The proposed method can find application in systems with code division multiplexing, including modern IoT systems.

    Keywords: time synchronization, direct sequence spread spectrum, broadband communication systems, Internet of Things, BER

  • Features of mm communications systems design

    The problems of mm propagation: rain attenuation,  depolarization and gaseous absorption are considered, and the estimate of the energy potential of wireless mobile data transport networks is given. The dependence on the output power of the distance and the total losses, and the necessary signal levels for different types of modulation being shown.  The estimate of the interfering transmitters effect of side lobes of the antenna is given.  

    Keywords: radio wave propagation, mm range, energy potential, rain clutter, side lobes, polar pattern