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Constantly growing volumes of the transmitted data leads to occurrence of new requirements to speed of transfer of telecommunication systems. However, the increase in speed of transfer, as a rule, conducts to expansion of a spectrum of signals. Besides there is a need in installation of new telecommunication systems, as a number of users grows. There is a problem of limitation of number of channels of transfer of the information.
This problem has two decisions: a lining of new cable lines or allocation of new channels of a broadcast. The lining of new cable lines demands the big expenses for construction and, actually cables. (Expenses for construction are especially great in conditions of low temperature and the big distances). All though the obvious advantages of a radio communication (speed of expansion, cheapness, mobility) are allocation of new channels of a broadcast, has a number of the problems connected to electromagnetic compatibility. Low frequency of carry signal defines low speed of the channel (criterion of Kotelnikov-Nyquist). Investigated hi-frequency and MICROWAVE RF it is strongly loaded by already existing systems of communication. Though, new ways of modulation of a signal (QAM SSQAM etc.) allow to get the big speed of transfer with spectra of the fixed strip of frequencies, the presence of free frequencies causes difficulties. So it is necessary to allocate new channels for higher frequencies. It should be noticed, that increase of frequency cannot be unmeasured as the noise of molecules of troposphere increases.
In masters work the problems of the construction of telecommunication systems on the basis of a liaison channel, a range of 47 GHz are considered.
Particularly the work is devoted to realization of parts with high lurl of linearities. Nonlinear parts of a liaison channel generate parasitic intermodulation components which worsen SNR systems and as affect the next liaison channels. It should be noticed that modern ways of modulation (QAM-256 QAM-512 SSQAM-256 etc.) demand the big linearity of any transformations of a liaison channel.
Realization of filtering frequency circuits. On the MICROWAVE realization of a set precisely narrowband is difficult, as increase of frequency sideband of a filter extends proportionally.
Realization of the highly stable generator of carrying frequency the most stable are generators based on quartz resonators. With increase of frequency the sizes of a crystal decrease, therefore there are no rather high-frequency quartzes. Multiplication of generated frequency at which the error of frequency is multiplied too is necessary.
Problems of the linear sizes. With increase in frequency an interference of radioelements is encountered. So reduction there is necessary to reduce the physical sizes of radioelements and connecting pathes.
Besides there is a lot of problems which are covered directly in masters work in more detailed.
I shall notice that work is fulfiled in couple with the student of group TKS-06mn Vorontzov A.A.
© Prokopenko V.A., 2007ã.