Results of non-stationary signal processing and interpretation using the simplest (ARX) regression model of real measurements with spaced antennas are presented. The obtained estimates of the mean velocity of the random medium travelling between ray-paths of spaced antennas coincide with those available in the literature. The considered approach makes it possible to determine the boundaries of the effective spectral interval of non-stationary signals more reasonably. This fact is critical for the task of the flow dynamical structure estimation and accurate evaluation of flows velocity. The Ideas discussed in the report may be of interest in the field of remote sensing with tools having a large-scale measuring volume allowing a diverse dynamic structure of the flows to exist inside it.

Kerr-Rice model (slice model) assuming the existence of correlation in the distribution of the scattering matter along the wave propagation path is considered in the report from the point of view of the possibility of the interpretation of real radar returns obtained at different wavelengths. Using a numerical model of slice scattering it is shown that it is impossible to get distributions like experimental distributions given in the report if a number of scatterers in the slice distributed as gamma, Gaussian or exponential functions and sizes of scatterers distributed as exponential or gamma functions.

An experiment on radio sounding of the circumsolar plasma by signals from the Mars Express spacecraft in 2013 was carried out in the period from March 4 through May 31. The investigated characteristics were the frequency of signals in the centimeter and decimeter ranges and the differential frequency. A number of events were recorded in which the intensity of the frequency fluctuations of the signals probing the plasma was several times higher than the background values. As shown by the analysis of observations of solar activity, such as an increase in the flux of X-rays and SOHO LASCO coronagraph data, this is explained by the passage of disturbed plasma streams generated in the solar corona through the spacecraft radio communication path with the Earth. The comparison of the radio transmission data with the results of measurements of the parameters of the near-Earth plasma using the Wind spacecraft in adjacent periods of time. As a result of the analysis of the data on the proton concentration, it became clear that sharp increases in both the average values and fluctuations of this characteristic were also observed near the Earth. The time lag between the events observed in the circumsolar and near-Earth plasma shows that the cause of the disturbances is the increased activity of the same coronal region rotating with the Sun.

The report is devoted to the discussion of possible amendments to the model of Rayleigh scattering applicable to the interpretation of radar echo from rarified media in the atmosphere.

Contents 1. IntroduCtIon (5) 2. tasks of radIo oCCultatIon experIments Inthe venus-d mIssIon (6) 3. methods of radIo oCCultatIon experIment (7) 4. data proCessIng teChnIque (8) 5. dIagnostICs of layered struCtures In the Ionosphere (9) 6. ConClusIon (11) referenCes (11) MARINER-5,-10, VENUS-9,-10, PIONEER-VENUS, VENUS-15,-16, MAGELLAN, VENUS-EXPRESS, AKATSUKI, more than 1500 radio transmissions of the Venosphere and Venus atmosphere were conducted [3][4][5][6][7][8][9].The amount of radio sounding data accumulated to date is relatively small (~1500 sessions), while the amount of radio sounding of the Martian RADIOLOCATION

In the present paper a basic concept of tools, measurement technique and a new mathematical model underlying data processing are briefly outlined envisioning their possible realization on the Venera-D mission. It is noted that the occultation experiments made with optimally matched parameters of RF-subsystem may pave the way to new and important findings.

In 2013 and 2015, investigations of the internal solar wind were carried out using the method of two-frequency radio sounding by signals from the Mars Express European spacecraft. The values of the S-and X-bands' frequency and the differential frequency were registered with a sampling rate of 1s at the American and European networks of ground-based tracking stations. The spatial distribution of the frequency fluctuation's level has been studied. It has been shown that the intensity of frequency fluctuation considerably decreases at high heliolatitudes. In some radio sounding sessions, quasiperiodic oscillations of sub-mHz band have been observed in the temporal spectra of frequency fluctuations; they are supposed to be associated with the density inhomogeneities, the sizes of which are close to the turbulence outer scale.

Estimates of the velocity of the chaotic medium motion using information of "narrow" spectral intervals of stationary random signals generated by the motion of such media on the sensors located at two points along the direction of medium motion are considered. The question about the physical meaning of the minimum spectral interval required for such measurements with a given accuracy is posed and discussed based on the main relations given in the article and formulated using the theory of homogeneous isotropic turbulence. It is shown, that within suggested relations the process of filtration may be described using a turbulent term and so the results of the filtration could be seen as a virtual turbulent dissipation. The latter allowed semiquantitatively describing the results of the numeric calculations presented in the article and forming the ways of the further development of the approach suggested which after appropriate updating might be called a "full filtered correlation analysis" (FFCA). In particular, a method of turbulent dissipation rate measurement by means of two (or more) filters with different bandpasses applied to signals in two points of cross-correlation measurements and an approach to the physically clear description of the optimal number of Fourier-terms in the representation of the signal passed the filter are outlined as well as the approach to a turbulence spectral shape evaluation. Apart from that, with the relations given in the article, the well-known fact that Doppler measurements are not applicable to the remote sensing with use of wideband signals as an information carrier as well as the reason why such measurements are applicable in the case of signals with narrow spectra receive its clear physical explanation. The latter allows forming the definition of a monochromatic signal as it is from the point of view of a cross-correlation analysis.

Experimental data of multiwavelength sounding in rains are considered in the report. It is shown that the probability density of radar echo in rains can deviate significantly from expected Rayleigh's shape at the millimeter wavelengths of the probing radiation as well as at the centimeter wavelengths in case of sounding with large pulse volumes.

This article offers one of possible approaches to the use of the classical correlation concept in Rayleigh scattering models. Classical correlation in contrast to three types of correlations corresponding to stochastic point flows opens the door to the efficient explanation of the interaction between periodical structure of incident radiation and discreet stochastic structure of distributed scatters typical for Rayleigh problems.

The main parameters and block diagrams of CW-microwave transceivers are considered. The advisability of leading in conception of energy potential is founded. Qualitative assessment of three ways of CW-microwave transceivers composing is done. The some features for application of CW-microwave transceivers are discussed.

The experimental data obtained in different years and by different scientific groups in rains (as rarified medium) are discussed in the article. It is shown that the results of such measurements are not complying with well-known Kerr-Rice model widely used for modeling backscattering of rarified medium. Short analysis of reasons for this is presented