卷 60, 编号 7 (2017)

The most promising technologies of signal forming and multiple access have been considered from the viewpoint of bandwidth-time resource usage. They include the full duplex technology, subcarrier forming method using a comb filter bank, the non-orthogonal multiple access method, and the sparse code multiple access method. The main existing implementation schemes of full duplex communication based on the analog and digital proper transmitter in the reception channel are described. The filtering multifrequency signal system using a bank of comb filters is considered. The spectrum of such signal is shown to have a much weaker out-of-band radiation as compared to the existing subcarrier forming techniques. The non-orthogonal multiple access method and the sparse code multiple access method are investigated, and relationships of the bit error rates as a function of the signal-to-noise ratio for communications systems based on these methods are presented. It has been shown that the multiple access methods under consideration are more effective in the bandwidth-time resource usage as compared to the existing technologies.

We analyze two options of combined systems for spatial signal processing in radars with phased antenna array, where the detection of noiseless point targets with background noise emissions is accompanied by the direction finding of their sources. In the first option the direction finding of noise emissions is based on the shape analysis of the adaptive radiation pattern of the phased antenna array, formed during the adaptive target finding with background noise emissions. In the second option the bearing angles are determined on the basis of maxima of “spectral functions” of different evaluations of correlation matrix, formed on the basis of input readings. An example how to build such a combined system for spatial signal processing based on general adaptive grid filter is presented. It is shown that the effect of simultaneous target finding in external noise background and direction finding of their sources is achieved by single utilization of the most complex tuning operation of the adaptive grid filter. This operation is same for both of these tasks, and it is easier comparing to solving these two problems separately.

The article proposes an iterative technique of calculation of energetic efficiency of triode high voltage glow discharge electron sources’, based on taking into account the influence of heating of anode plasma by the accelerated electrons of electron beam and by the slow secondary discharge electrons, reflected from the anode. The increase of temperature of anode plasma influences its’ volume, as well as the concentration and mobility of ions’ in it. Therefore, the proposed model allows obtaining the corrected values of discharge current and energetic efficiency of electron sources by taking into account the thermodynamic parameters of anode plasma. In addition, one of the advantages of proposed iterative calculation technique is that the model is closed and self-consistent, therefore, it does not demand use of approximated data about the thermodynamic parameters of discharge plasma from references.