April 9, 2021

Abstract:

RKPNI is Russian Complex of Receiving of Science Data. It was created in frame of oint ESA-Roscosmos space project ExoMars and it is intended to support the network of ESA’ ground stations for receiving of science data from Martian Trace Gas Orbiter (TGO) spacecraft.

The geography of the RKPNI is quite wide: it covers two ground stations with 64-meter antennas located in the Moscow and Tver regions, and in addition to this, the system nodes are located in Moscow, Khimki and ESOC (Darmstadt, Germany).

RKPNI built jointly by Russian and ESA specialists since starting of nominal science program of ExoMars TGO mission at the end of 2018 till now it provides receiving of significant part of TGO science data and is a successful example of international cooperation in the field of deep space exploration.

The report describes the technical and organizational problems that the authors had to overcome when creating the system, system architecture and principles of operations. Prospects for the evolution of the RKPNI, including uplink possibilities for the ExoMars RSP mission, as well as the use of RKPNII in other space projects are also discussed in the report.

Abstract:

Currently, 64-meter radio telescopes Kalyazin and Bear Lakes (OKB MEI) are being prepared for participation in experiments on measuring the spacecraft coordinates using the Delta-DOR method and carrying out VLBI experiments on various scientific tasks: coordinate and navigation measurements, calibration of interferometers, research of media propagation of radiation, support of space missions in the reception and transmission of scientific information, etc.

Broadband converters for recording and transmitting data have been developed and manufactured. These devices perform preliminary conversion of data into RDEF and VDIF formats depending on the task of the experiment. Two-channel converters allow to record a signal with a maximum frequency of 2 GHz in a bandwidth of up to 256 MHz.

The new equipment was tested in VLBI-experiments on observation of extragalactic radio sources. Broadband converters were included in the standard radio tracts of the Kalyazin and Bear Lakes antennas at a frequency of 8.4 GHz. The scientific task of the experiment was to calibrate the interferometer and measure the projections of the baseline and the instrumental delay.

The experimental data were processed using a correlator developed for multiplying the complex signals of interferometric experiments. The XF and FX correlator algorithms have been implemented, and new methods for automatic search for the correlation signal and the tracking correlator algorithm have been tested.

Based on the results of processing the data of VLBI-experiments, the lengths of the baseline projections and the value of the instrumental delay were estimated. The discrepancy between the obtained and specified projections is less than 3 meters, and the dispersion does not exceed 7.5 m, which is significantly less than the error in measuring the delay in a linear measure.

The developed equipment - a broadband converter and a correlator - made it possible to apply the method of in-phase summation of signals received by two antennas. This method of summation of areas allows to achieve an increase in sensitivity by increasing the area of the receiving system. An experiment was carried out to receive, summarize and reproduce the signal of the space station TGO of the ExoMars mission. An increase in Eb / N0 was obtained with respect to the average value of the original signals by 2.6 dB.

The paper presents the results of experiments and discusses the possibilities of developing technical solutions and scientific application of broadband converters and a correlator.