Compact troposcatter station for transhorizon communication Michael Ilchenko National Technical University of Ukraine “I. Sikorsky KPI” Kyiv, Ukraine e-mail: Ilch@kpi.ua Serhii Kravchuk National Technical University of Ukraine “I. Sikorsky KPI” Kyiv, Ukraine e-mail: sakravchuk@ukr.net Mykola Kaidenko National Technical University of Ukraine “I. Sikorsky KPI” Kyiv, Ukraine e-mail: kkk610@ukr.net Valentin Khytrovskyy Scientific and Production Enterprise “Cinco” Kyiv, Ukraine e-mail: synco@ri-orion.kiev.ua Abstract — The results of the development of a modern domestic compact troposcatter radio relay station, both general and special purpose (dual purpose) are presented. The station is characterized by low power consumption, compact dimensions and low weight due to the use of the newest element base of microelectronics in extremely high frequency range, modern radio technologies for the formation and transmission of radio signals through the troposcatter channel. The station has following main technical characteristics: operating frequency range - 4.4-5.0 GHz; maximum data rate of reception/transmission of the digital information stream is up to 8 Mbps; protocol and interface for data transmission is IP (TCP/IP), Ethernet; there is a built-in system of functional control without radiation in the air; a range of the radio link is up to 120 km. Keywords — compact troposcatter radio relay station; troposcatter channel; software-defined radio; data rate; transhorizon communication I. INTRODUCTION Ground-based radio-facilities capable of creating radio links for over-horizon communication are widely used, in particular for the military (in strategic, operational and tactical control links), special services, rescue services and emergency situations [1-3]. Among the over-horizon communication systems, special attention is paid to the so-called troposcatter radio-relay stations (TRRS), which are much more difficult to implement than radio-relay of line-of-sight systems. The principle of operation of such troposcatter radio links is based on two mechanisms of radio waves propagation: at intervals of more than 70 km, on the scattering of radio waves by inhomogeneities in the troposphere; At short intervals – on the diffraction propagation of radiowaves. Main features of such tropospheric propagation of radiowaves, related to the physical nature of this phenomenon, is a very large attenuation of the radio signal in the area of propagation and fading of the signal at the input of the receiver, which are selective in frequency [4-6]. Here, the multipath effect manifests itself, which is due to the different path lengths of the beams passing through the volume of natural local inhomogeneities in the atmosphere on which radiowaves can be scattered. Earlier troposcatter communication systems had a radio channel capacity sufficient to transmit voice and small data streams over long distances without intermediate repeaters. These systems were characterized by the use of powerful power amplifiers, very large mirror antennas, which were cumbersome for deployment and difficult to transport. One of the cardinal solutions for leveling these disadvantages while maintaining the necessary noise immunity in conditions of multipath fading is the creation of effective portable TRRS of a new generation, based on the principles of construction, which are presented in [7-11]. The current requirements for troposcatter equipments are as follows: should be small, light, easy to deploy and manage, and should be able to provide high speed data transfer of digital traffic to IP. The implementation of such portable TRRS requires the development of appropriate high- performance station equipment [12]. At the same time, it is necessary to solve a number of scientific and technical problems, in particular: the adaptation of the transmitted signal to the propagation conditions of radio waves; protection of the communication channel from radio interference by adapting the frequency of the emitted signal to the interference situation; the organization of digital channels of service communication, the channel of remote supervision and telesignalization; remote control of operation modes and control of communication quality. Currently, the task of linking remote sites deprived of infrastructure remains relevant, and work on creating effective TRRS has been intensified abroad. A number of foreign companies have presented their development of such small TRRS. In particular, TeleCommunication Systems achieves unprecedented performance and Comtech Systems have