The work is devoted to the estimation of errors in determining the coordinates of the location groundbased radio emission sources at satellite radio monitoring. The proposed method of determining the coordinates of the source using angle-measuring methods based on one small spacecraft was chosen as the basis. The measured angular parameters were determined, which affect the accuracy of determining the latitude and longitude of the source. Calculations and analysis of the influence of determining the scanning angles of antennas in different planes on the errors in determining the coordinates of ground sources have been carried out. The obtained results of error calculations will allow us to determine the requirements for methods and equipment of radio monitoring to ensure a given accuracy in determining the location of ground-based radio emission sources. Radio frequency spectrum, radiomonitoring, radio-electronic means, satellite radio monitoring, source DTESI 2023: Proceedings of the 8th International Conference on Digital Technologies in Education, Science and 0000-0002-0143-085X (A. Kulakayeva); 0000-0002-7808-5273 (A. Aitmagambetov); 0000-0002-7808-5273 (Zh.
of radio emissions, low Earth orbit satellite, geolocation
The rapidly growing number of operating radio emission sources and radio networks is
significantly complicating the electromagnetic situation in conditions of a shortage of the radio
frequency spectrum (RFS) and requires improvement of the functions and mechanisms of the
radio monitoring system [
RFCs such as: software defined radio, cognitive radio, dynamic/opportunistic spectrum access, spectrum sharing and licensed/unlicensed spectrum aggregation and so on. All these approaches and methods are aimed at achieving optimal use of the RFS and to improve the functions and mechanisms of the radio monitoring system. The current radio
monitoring systems are implemented on the basis of ground-based radio
monitoring facilities [
Thus, one of the obvious ways to solve the problem of increasing the efficiency and expanding
the control area of radio monitoring systems is the creation of satellite radio monitoring systems
based on low-orbit small spacecraft (SS) [
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subject to many of the risks that other terrestrial systems and communication networks are
exposed to, including factors such as accidental damage, theft, etc. Therefore, such systems should
be used in order to increase the efficiency of the radio monitoring system by using satellites as
radio monitoring stations [
In radio monitoring, a special place is occupied by determining the location of radio emission sources (RES), which is a complex task requiring the use of an automated complex of special equipment with specified technical characteristics to determine the location of the studied radio emission sources with maximum accuracy. Location estimation methods are necessary to determine the location of radio emission sources. In radio monitoring systems, effective methods and algorithms are needed to accurately determine the location of radio emission sources. Currently for determine the location of RES, such methods are known based on the level of the received signal strength (RSS - received signal strength), the phase of the carrier signal (POA carrier phase of arrival), the time difference of arrival (TDOA), the angle of arrival (AoA) (or the direction of arrival DOA), the frequency difference of arrival (FDOA), Doppler frequency difference (DD) and combined methods consisting of two or more of the above methods The classification of the most common methods for determining the location of radio sources is shown in Figure 1.
However, in practice, combined methods consisting of two or more of the above methods are often used to increase reliability in determining the location of radio sources. This approach makes it possible to eliminate the disadvantages of one method by supplementing the properties of the other [13-16].
Thus, to date, TDOA-FDOA and other combined methods have become the most widespread
in satellite systems. Such methods of determining the location of radio emission sources require
several low-orbit SS, which is inefficient from an economic point of view. Therefore, the method
of determining the coordinates of the source using the angle-measuring method, which is
proposed in [
The studies carried out in [17] showed that the application of the Kalman filter to the implementation of the signal detection task turned out to be a successful solution. However, when determining the location of radio emission sources with any degree of perfection and accuracy of on-board radio measuring equipment, as well as regardless of the thoroughness of the experiment, the measured value will always differ from the true one, since errors are inevitable when measuring.
When determining the location of a RES using one low-orbit SS with two active phased antenna arrays (APAA) on board, the accuracy of estimating the coordinates of radio emission sources will depend on a number of factors such as: • signal level (signal-to-noise ratio) at the input of on-board measuring equipment; • errors in determining the coordinates of the SS; • errors in fixing phase angles between adjacent APAA elements Δφ; • the width of the swinging sector of the APAA beams.
In this paper, the estimation of errors that will occur when determining the location of radio
emission sources using a single low-orbit SS is based on the angle-measuring method, with the
use of APAA-type scanning antennas on board the SS to determine the bearings on the RES. At the
same time, all coordinates of radio emission sources will be determined using the developed
algorithm, which is considered in [
In this paper, the area of radio monitoring is the territory of the Republic of Kazakhstan, which is in the range of values from φ = 40° to φ = 56° north latitude (the average value of the radio monitoring area is φ = 48°), as well as in the range of values from ν = 45° to ν = 87° east longitude.
When determining the location of the RES by the algorithm and program presented in [
After determining the latitude of the RES (φ) according to the algorithm and program
presented in [
Also, when calculating, it is necessary to take into account the longitude lines, which are called meridians. The length of the meridian is equal to 40,008.55 km. To find the length of one degree in any meridian, it is necessary to divide 40,008.55 km by 360°, we get 40,008.55 km / 360° = 111,134861111 km/° (111134,861111 m/°). It turns out that the length of 10 = 111,134861111 km / ° or 111134,861111 m / ° and this length is the same in all meridians. Therefore, when calculating the error in determining the longitude of radio emission sources, the length of 10 will be the same everywhere. The calculated values of the longitude determination error are presented in Tables 2 and 3. The dependences of the error on the errors in determining the scanning angles that arise when determining the longitude of the location of the RES depending on the scanning angle µ (correction sign "+") are shown in Figures 3 and 4. b) Figure 4: Errors arising in determining the longitude of radio emission sources a) in degrees and b) in linear dimensions (correction sign "+") The dependences of the longitude error on the errors in determining the scanning angles µ that occur when determining the longitude of the location of the RES (correction sign "-") are shown in Figures 5 and 6.
Thus, when determining the coordinates of radio emission sources, the errors will grow linearly depending on the errors of the scanning angles β1 and β2 and on the angle µ, on which the choice of longitude correction angle η2 or η1 depends, which are shown in Figures 7 and 8.
The use of spacecraft in radio monitoring systems will make it possible to determine the parameters of signals and the location of radio-electronic means over a large area with a diverse terrain, which will increase the efficiency of radio monitoring systems. Therefore, taking into account and estimating errors that occur when determining angular parameters using a single low-orbit SS is a very important task, since the accuracy of determining the location of the RES depends on the values of these errors. As the calculations have shown, the errors made in this work will grow linearly depending on the errors in determining the scanning angles. Therefore, in order to minimize these errors, it is necessary to carry out multiple measurements of the coordinates of the ground source of radio emission, in which the bearings are determined at several points of the orbit in the visibility zone of the low-orbit SS.
When estimating the errors that will occur when determining the location of radio emission sources using a single low-orbit SS, it was found that the errors will grow linearly depending on the errors of the scanning angles β1 and β2 and on the angle µ, on which the choice of longitude correction angle η2 or η1 depends.
The obtained results of error calculations will allow us to determine the requirements for methods and equipment of radio monitoring to ensure a given accuracy in determining the location of ground-based radio emission sources.
To improve the accuracy of determining the coordinates of radio emission sources, it is necessary to find new methods of angular measurements, or to carry out multiple measurements of the coordinates of a ground-based radio emission source, in which the bearings are determined at several points of the orbit in the visibility zone of a low-orbit spacecraft.
In addition, in order to implement radio monitoring systems based on small spacecraft, it is necessary to conduct a number of studies related to the evaluation and analysis of signals received by an on-board measuring receiver, evaluation of the accuracy of various location determination methods, selection of spacecraft designs and orbits.
Notes in Computer Science, Springer, Cham, vol 12980, pp. 419-427, doi:10.1007/978-3030-87595-4_31. [13] Merrill I., Skolnik. Radar Handbook, Third Edition. - McGraw-Hill Education, 2008. ISBN: 9780071485470. [14] A. G. Dempster, E. Cetin (2016). Interference Localization for Satellite Navigation Systems, in: Proceedings of the IEEE, 104(6), pp. 1318-1326. [7439734]. https://doi.org/10.1109/JPROC.2016.2530814. [15] L. Zhao, G. Yao and J.W. Mark (2006). Mobile positioning based on relaying capability of mobile stations in hybrid wireless networks, in: IEE Proc.-Commun., vol. 153, No. 5, October. [16] V. O.Sotnikov, F. T. Zap (2019). Analysis of methods for estimating the position of a groundbased radio source in a satellite communication system with direct retransmission, in: Collection of scientific articles based on the results of the International Scientific Forum, vol.1, p. 91-100. [17] A. Kulakayeva, A. Aitmagambetov, Y. Daineko, B.Medetov, Zh. Ongenbayeva, (2022).
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