The Millimetron Space Observatory will be equipped with the cryogenically cooled instrument for a Space-Earth Very Large Baseline Interferometry (S-E VLBI). It will be a multi-channel heterodyne receiver with 7mm, 3mm, 1.3mm and 0.8mm channels. The VLBI instrument will have a multi-frequency capability, provided by signal splitting in the input optics and by back-end functionalities. The optical design is shown in this report.

В работе рассмотрены научные и технические перспективы и возможные направления развития субтерагерцовой астрономии в Российской Федерации. Предложена концепция создания субтерагерцовых инструментов в виде универсальной компактной антенной решетки для размещения на территории России. На базе концепции такой антенной решетки возможна реализация нескольких космических проектов субтерагерцового диапазона нового поколения – космического интерферометра и телескопа, расположенного на поверхности Луны. Наземные антенные решетки смогут выступить в качестве поддержки режима интерферометра со сверхдлинной базой обсерватории «Миллиметрон».

This paper addresses the scientific and technical prospects and potential directions for the development of subterahertz astronomy in the Russian Federation. The concept of creating subterahertz instruments in the form of a universal compact antenna array for placement on the territory of the Russian Federation is proposed. It is possible to implement several space projects in the subterahertz range using such an antenna array, including a space interferometer and a telescope on the surface of the Moon. Ground-based compact antenna arrays will be able to act as a support for the very long baseline interferometer mode of the Millimetron observatory.

The data transmission validity under conditions of log-normal amplitude fluctuations controlled by the Fresnel diffraction in the spacecraft–ground tracking station transmission line in the case of coherent reception of millimeter-range signals. The optimum signal transmission frequencies in the tropospheric channel are separated by the criterion of minimizing the of error probability and the possibilities of reaching high transmission rates are analyzed.

Millimetron space observatory will be equipped with the cryogenically cooled instruments for a Space-Earth Very Large Baseline Interferometry (S-E VLBI). It will be a heterodyne multichannel receiver including 7mm, 3mm, 1.3mm and (presumably) 0.8mm channel. Two low frequency channels will be based on HEMT amplifiers, while for the high frequencies superconductor-insulator-superconductor (SIS) receivers will be utilized. The VLBI instrument will have a multi frequency capability allowing simultaneous observation using several channels. This mode has a high potential for improving of black hole event horizon observations due to phase transferring capabilities. The multi frequency observation will be provided by a signal split in the input optics and by back-end capabilities.

The data transmission reliability under conditions of logarithmically normal (lognormal) amplitude fluctuations defined by Fraunhofer diffraction in the spacecraft—ground tracking station communication line is analyzed using a coherent method of signal reception in the millimeter range. At fixed radio signal paths in the troposphere, optimum signal transmission frequencies are shown by the error probability minimization criterion. The minimum effect of hydrometeors on the communication quality under Arctic climatic conditions is shown.

The possibility of using millimeter-wave (MM) satellite communication lines in the Arctic to ensure reliable and high-speed communication is considered. The main problem for the application of MM waves is the possible meteorological conditions for the propagation of radio waves in the cold. Vertical profiles of meteorological data for a pair of islands in the Arctic Ocean were used to calculate molecular absorption on a possible link. A very simple model of attenuation of radio waves in rain on such a line is proposed. The satellite orbits for calculating the line attenuation margin were assumed as in the existing satellite system Gonets operating at frequencies of 300/400 MHz. The results of calculations show that satellite communications in the MM band are possible in the Arctic.

The article describes the main features and algorithms of Astro Space Locator (ASL) software package. This high performance package has a user-friendly graphical interface and it is used for VLBI data processing and reduction. ASL supports data editing, calibration, multi-frequency analysis, standard and multi-frequency VLBI imaging.

Algorithms ensuring high-speed and reliable data transmission under lognormal amplitude fluctuations (described by Fraunhofer diffraction) in the spacecraft–ground tracking station line for coherent and incoherent reception of signals have been considered. An advantage of the coherent reception of millimeter-range signals with a random error-correcting code has been indicated.

ИМИТАЦИОННОЕ МОДЕЛИРОВАНИЕ ТЕЛЕКОММУНИКАЦИОННЫХ СИСТЕМ ВЫСОКОСКОРОСТНОЙ ПЕРЕДАЧИ ДАННЫХ ПО АТМОСФЕРНОМУ РАДИОКАНАЛУ В ЧИСТОЙ АТМОСФЕРЕ С ПОМОЩЬЮ МИЛЛИМЕТРОВЫХ ВОЛН В ИНТЕГРИРОВАННЫХ ЦИФРОВЫХ СИСТЕМАХ СВЯЗИ

The algorithms for achieving a practical increase in the rate of data transmission on the space-craft–ground tracking station line has been considered. This increase is achieved by applying spectral-effective modulation techniques, the technology of orthogonal frequency compression of signals using millimeterrange radio waves. The advantages and disadvantages of each of three algorithms have been revealed. A significant advantage of data transmission in the millimeter range has been indicated.

The action of fadings on the noise immunity of digital communications in a channel with Nakagami signal fading when radio waves propagate through a medium with random nonuniformities (in particular, in satellite communications when the radio waves pass through the troposphere), is investigated. The gain in noise immunity from the use of intermittent data transmission compared with existing methods of reception is estimated.

The action of fading on the noise immunity of digital communications in a generalized Rayleigh (Rician) channel when setting up communications under multipath signal propagation conditions is investigated. The gain in noise immunity and spectral efficiency from the use of interrupted data transmission and the complexing of the interrupted communications with diversity reception compared with existing methods of such reception is estimated.