Abstract
The article examines mobile digital troposcatter stations and mobile combined digital radio engineering stations, which will include systems of spatially diversity signals. This is a well-known method of increasing the stability of communication and obtaining the necessary quality indicators when transmitting signals through multipath channels. The methods of receiving spatially diversity signals can be classified as diversity reception with combining signals by microwave frequency, intermediate frequency and the main working frequency band. Methods of combining spatially diversity signals: automatic selection; linear assembly; optimal assembly. The article examines in detail the signal composition scheme in the linear path before the demodulator and after the demodulator. The results of the research showed that the best opportunities are in linear assembly. At the same time, it was noted that autophasing methods play an important role: automatic control of the phases of heterodyne microwave signals and automatic phasing of composite signals at an intermediate frequency. With optimal composition, theoretically the greatest gain in terms of signal – to – noise ratio is obtained. However, the linear combination compared to the optimal gives a lower signal-to-noise ratio at the output of the combiner by only 1 dB. Therefore, for nodal and high-speed mobile digital troposcatter stations, the use of linear combination as a method of combining diversity signals is recommended. The article analyzes several structural schemes of the receiving path for spatially diversity signals with intermediate frequency combination in mobile digital troposcatter stations. Note that reception with spatially diversity of antennas continues to be the main means of improving communication stability on troposcatter communication lines during the transmission of digital signals. The article discusses the methods of receiving and combining spatially diversity signals in which there are no interruptions in communication due to switching. Linear combination are widely used in modern mobile digital troposcatter and combined radio engineering systems, the components of which is the troposcatter component.
Published Version
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