The presented work analyzes the existing structure of data processing in airspace surveillance radar networks, which includes sequential execution of data processing stages (including signal processing and primary data processing stages). Based on the analysis, it is shown that the lack of inter-stage optimization leads to a decrease in the quality of data processing. Which in turn leads to a decrease in the quality of information support for consumers in the existing information network of airspace surveillance radar systems. The paper synthesizes an optimal structure of joint processing of signal data and primary processing data in airspace surveillance radar systems networks. The synthesized structure of joint processing of signal data and primary processing data allows implementing two methods of data processing: combining decisions at the level of data on detection of received signals from surveillance systems; combining at the level of making decisions on detection of air objects. The method of data processing by an airspace surveillance radar system, in which data are combined at the level of making decisions on detection of air objects for each signal data processing channel, ensures inter-stage optimization of network radar data processing and primary data processing. The proposed method has significant advantages in the quality of surveillance system data processing in comparison with the one currently used. This ensures an increase in the quality of information services for consumers of the considered information network of radar surveillance systems of airspace.

The work analyzes the process of functioning of aerial surveillance search radar systems: friend or foe identification systems, secondary surveillance systems, radar systems near navigation. This demonstrates that which construction existing radar interrogation systems can be represented as an asynchronous network for transmitting radar information, also an order processing signals interrogations can be described in a form a one-channel queueing system with failures. Using of simple coding of request and/or response signals does makes impossible ensuring a given quality level of service of airspace surveillance and traffic control systems in the face of significant intra-system errors, and also intentional interference correlated or/and uncorrelated. This article provides the mathematical description of a request servicing process and examines the dependence of the probability of an error in the system on the length of a data packet. An influence not only single and group errors in the radar information transmission channel was taken into account, but also the requirements for the permissible number of repeated requests. An algorithm for adaptive control of the transmission of radar information was proposed. This algorithm involves analyzing the characteristics of the wireless data transmission medium and makes it possible to dynamically change various parameters of the access control level to the physical medium depending on changes in the signal propagation environment. Consequently, it becomes possible to find optimal settings for a specific distribution environment, ensuring optimization a length а data packet of packets data being transmitted.

One interesting idea that could improve wireless communication systems is reconfigurable intelligent surfaces or RIS. To control the spread of wireless signals, RIS uses a plethora of tiny, inexpensive, and customizable reflecting devices. Signal strength, energy consumption, spectrum efficiency, and adaptability to changes in the wireless environment can all be improved by altering the phase shift of the reflecting elements. This is how RIS works. 5G and beyond, the IoT, and smart cities are just a few of the many potential uses for RIS. More study is required before this technology can reach its full potential since it is still in its infancy. Still, RIS is going to be big in the next generation of wireless networks. A great deal of excitement has enveloped the whole 6G development industry. There has been no shortage of grandiose and frequently unfounded assertions that, in reality, the creation of a full-duplex 5G technology that can introduce new services is just around the corner, even though self-interference cancellation schemes for full-duplex communications and the difficulties of building full-duplex base stations have long been known.

In the presented work, based on the classification of airspace surveillance radar systems in the form: independent non-cooperative radar surveillance, independent cooperative radar surveillance, dependent cooperative radar surveillance; the quality of determining the coordinates of air objects by the systems under study was assessed. The place and role of these information systems in the information support of airspace control and air traffic control systems is shown. From the calculations carried out, we can draw the following conclusion that the sensitivity of measuring the height of an airborne object significantly depends on the geometry of the location of receiving points of a synchronous network of radar surveillance systems. As the distance between receiving points increases, the area covered by curves of equal sensitivity increases. It is substantiated that when using equal weight in the accuracy of range measurement and in measuring the altitude of an airborne object, the accuracy of the synchronization of the time scales of the receiving points is the value achieved by modern means of time synchronization. The use of the given methodology for assessing the quality of measuring the coordinates of air objects in a synchronous network of cooperative radar surveillance systems for airspace allows us to put forward requirements for the synchronism of time scales in a unified synchronous information network of radar surveillance systems when measuring the coordinates of air objects. It is shown that the price for improving the accuracy of determining the coordinates of air objects by a synchronous network of cooperative radar systems is the complication of the system due to an increase in positions, an increase in the number of transceiver paths, the need to synchronize emission processes, receive signals and control viewing modes.

An expression for the effective data transfer rate in the response channel of a secondary radar under the action of intentional and unintentional correlated and uncorrelated, impulse and fluctuation interference in the channel is obtained. And also the influence of the main four factors on the decrease in the data transfer rate was evaluated: interference, analysis time at the receiving point, waiting time for confirmation at the transmitting point, and exceeding the allowable value of the number of retries. It is shown that the optimal size of information transmission through the channels of the secondary radar is largely determined by the intensity of interference. An algorithm for achieving the optimal transmission packet size is proposed.

In the presented work, based on the general characteristics of the three main types of radar surveillance of airspace, including independent non-cooperative surveillance, independent cooperative surveillance and dependent cooperative surveillance, the data integrity of the information of dependent cooperative surveillance of airspace was assessed. It is shown that the integrity of the coordinate data of the dependent cooperative airspace surveillance system is determined by the probability that information about the coordinates of the observed air object, transmitted in the messages of the dependent cooperative airspace surveillance system, used by consumers for the purpose of air traffic control and airspace control, should not contain undetected errors, the number of which exceeds the decision threshold.

The paper examines the existing systems of radar identification based on the "friend-foe" feature from the point of view of immunity evaluation. Currently, there are two systems of the radar identification based on the characteristic of "friend-foe", namely, the "Password" and MkXIIA. They are the radar identification systems based on the "home-foreign" feature. The former of the specified systems operates in a frequency range that differs from the frequency range of secondary radar systems, while the second one operates in the frequency range of secondary radar. These systems are ones of the main information resources of the airspace control system and are built on the principles of a one-channel or two-channel information transmission system. It allows the interested party, both an unauthorized use of this information resource for remote determination of the coordinates of aerial objects, on the one hand, and twisting the information of these information resources, on the other hand, which leads to unpredictable results. The purpose of the work is to assess the immunity of existing radar identification systems based on the "friend-foe" feature. The analysis of the interference protection of existing systems for the object radar identification based on the "friend-foe" feature, built on the principles of interrogative and non-interrogative information systems presented in this work, showed that the use of rectangular radio signals with time-pulse modulation as request and response signals emitting by air objects, has low immunity and excludes the energy stealthiest of the respondents of aerial objects. And, as a result, it allows for unauthorized calculation of the coordinates of air objects by the interested party based on the emitted identification signals on the basis of "friend-foe".

This document presents the synthesis and analysis of the optimal interrogation signal detector in aircraft transponders of interrogation radio engineering systems under the action in the interrogation channel of interrogation signal streams emitted both along the main and side lobes of the interrogator antenna, as well as deliberate uncorrelated and correlated interference. It is shown that taking into account the elements and their arrangements in the structure of the detector that evaluate the amplitudes of useful signals, as well as the excess of the amplitudes of superimposed interfering signals over them, makes it possible to stabilize the probability of false alarm when useful request signals are detected and, as a result, to improve the quality of detection of interrogation signals in aircraft responders.

The paper demonstrates the important role of using radar systems in many spheres of human activity to solve complex and important problems of society. The paper examines and analyzes the capabilities of the MATLAB program package applying to the design, modernization and research of radar systems. The analysis performed shows that the MATLAB software package is a powerful tool for modeling, researching and designing radar systems for various purposes. Also, attention is paid to the MATLAB Radar Toolbox, which includes a wide range of available models that can be modified. The Radar Toolbox provides rapid modeling, upgrading and prototyping of standard and upgraded radar systems. Using the MATLAB to research radar systems is impossible without understanding the principles of construction and operation of radar systems. It is also necessary to know the features of using the MATLAB function to describe, present and model structural elements and processes in radar systems. The paper presents the main functionality and possible options for implementing models in the MATLAB for modeling and studying radar systems. The given list of model options is not exhaustive and final and can be expanded and supplemented depending on specific tasks and requirements for implementation.

The structure of information support for the airspace control system based on combined radar surveillance systems has been substantiated and investigated. This makes it possible to improve the quality of the detection of air objects, as well as to assess the accuracy of the location of the detected air objects. As a result, this improves the quality of information support for decision-makers in the airspace control system.

In the presented work, based on the Neyman-Pearson criterion, the optimal structure for detecting request signals in an aircraft responder of the SSR (IFF) system is synthesized, in which the optimization of the detection of signaling information is carried out not only in time, but also in the spatial parameters of the received request signals, and also takes into account the relative throughput of the aircraft responder. It is shown that the interchannel fusion of the results of detection of the component pulses of the request signal is more preferable in comparison with the existing algorithm for merging the results of the detection of the request signal, since it allows to improve the quality of detection of the request signals and somewhat reduce the dependence of the probability of detecting the request signal on the relative throughput of the aircraft responder.

In the presented work, the relative throughput of both a ground-based range transponder and the entire short-range radio engineering system is estimated under the action in the range channel of the total flow of range request signals. And also considered the requesting signals for unauthorized use of the rangefinder channel transponder by the interested party under the action of chaotic impulse noise flow. The evaluation was carried out on the basis of the representation of the channel for measuring the range of short-range radio engineering systems in the form of a non-synchronous network. We assume that the range request signals are serviced by an open single-channel queuing system with refusing according to the service scheme of the first correctly received range request signal.

Patient signals produced from a physical device, such as electrocardiography (ECG), which records the electrical activity of the heart, are vulnerable to keep noise due to various physical constraints of acquisition devices. It is critical for the detection and diagnosis of a variety of diseases. An ECG signal should be displayed as clean and clear as feasible due to its relevance in assisting physicians and doctors in making appropriate judgments. ECG is vulnerable to many types of noise because it is an electrical signal. To improve the quality of assistance for consumers Info a surveillance system by cooperative surveillance systems, high-quality data processing by the observed surveillance systems is required, which predetermines the requirement for high noise immunity of the latter. At the same time, the basics of building cooperative surveillance systems as a network of two-channel asynchronous information communication systems which include numeral of transmitting and receiving process using diverse frequency limits for reception and transmission, failure-prone open single-channel queuing systems, and request signals do not allow to provide the required the noise resistance of the systems under consideration. This paper first gives a characterization of request and interference signal flows in cooperative surveillance systems and briefly examines the features of request signals and their effect on the immunity of cooperative surveillance systems. Then, it calculates the noise resistance of the demand signals of the cooperative surveillance systems for the probabilities of errors: signal skipping; First- and second-degree false alarms in the case of unrelated events, unintended and intra-system impulse interferences in the request channel

In the presented work, a method is proposed to increase the interference immunity of the range channel of short-range navigation systems, in which a successive transition is made from servicing the request signals of individual range requesters to servicing individual amplitude channels of the received request signals on the range transponder. This made it possible to switch from servicing individual range request signals to servicing individual range requesters and thereby exclude the possibility of paralyzing the aircraft transponder by deliberate correlated interference of the required intensity by the interested party and, as a result, increase the interference immunity of the range channel of short-range navigation systems.

This study explores aircraft transponder data processing in identification friend or foe systems using the Neumann-Pearson criterion. The multi-channel reception of request signals and the limited relative transmission capacity of aircraft transponders due to the currently prevailing use of the single-channel failover queuing mode are found to deteriorate the system performance. Theoretical models are proposed for request signal processing in situations when previous channel decisions on detecting request signals or pulse components are merged across channels. Data processing is optimized for time and spatial parameters of request signals and with due regard to the aircraft transponder relative transmission capacity. Inter-channel fusing of request signal pulse detection results are shown to be preferable to the currently used fusing algorithm that operates with request signal detection results since they enhance detection efficiency and reduce its dependence on the aircraft transponder relative transmission capacity.

. In the presented work, a method is proposed for increasing the relative throughput of requesting radar systems for monitoring airspace in which a successive transition is made from servicing a separate requester of radar systems to servicing a network of requesters. They observe this air object by forming an analysis time interval on the aircraft's responder, detecting request signals at this time interval. If at least one request signal is detected in the time analysis interval, at the end of the analysis time interval, a response signal is emitted, which includes the spatial coordinates of the given air object. This makes it possible to exclude the possibility of paralyzing an aircraft transponder by a deliberate correlated interference of the required intensity by the interested party and, as a result, to increase the relative throughput of requesting radar systems for airspace monitoring.

In the work presented, a comparative assessment of the accuracy of measuring of aerial objects coordinates was carried out based on the gradual transition from angle-range measuring to range-ranging measurements of the aerial objects coordinates due to the implementation of a synchronous information network of existing range-finding radio beacons. It is shown that the use of rangefinder-rangefinder calculations in radio engineering short-range navigation systems allows increasing the accuracy of estimating the coordinates of aerial objects. This also makes it possible to carry out a transitional transition to interference-protected short-range radio systems.

In this work, the capacity of the transponders of the indication channel of short-range navigation systems is estimated under the action of intra-system and intentional correlated and uncorrelated interference in the request channel, based on the presentation of the indication channel of short-range navigation systems as an open single-channel queuing system with failures. It is shown that the implementation of time gating of the incoming signals "indication request" with a time gate for receiving the response signals of the range of radio beacons can reduce the intensity of the formation of response signals and, as a result, increase the throughput of the indication channel.

In the presented work, the analysis of the influence of interference and accidental loss of the received response signals due to the final availability factor of the aircraft responder of the airspace surveillance requesting systems on the time position of the decoded signals is carried out. It was shown that a decrease in the readiness factor of an aircraft responder, as well as the probability of detecting single pulses of the used response signals in requesting radar systems for observing the airspace, leads to an increase in both the delay of the output pulses and to an increase in the magnitude of the dispersion. The method of decoding response signals with inter-period pre-processing of response signals is more preferable due to the fact that it has both a shorter delay time and a variance in the estimation of the delay time in comparison with the method of decoding with subsequent inter-period processing of the received signals.

The paper analyzes the principles of construction and structure of "friend or foe" identification systems. It is revealed, that the party, interested in the existing system, has the ability of unauthorized use of this information resource for long-range determination of air objects coordinates, on the one hand, and distortion of information of this information resource, on the other hand, which leads to unpredictable consequences. It is shown, that the most vulnerable place in the "friend or foe" identification systems is the aircraft transponder, which significantly affects noise stability and noise immunity of the identification systems of air objects. The paper proposes a method of hereditary transition to noise-immune "friend or foe" identification systems based on synchronous networks of identification systems, which allows expanding significantly the methods of servicing requests and methods of constructing systems. This method of constructing identification systems eliminates the existing problem of dispersed identification systems, as well as the problem of temporal matching of signals coming from primary and secondary radar systems. The proposed method of hereditary transition to noise-immune "friend or foe" identification systems makes it possible to exclude the possibility of unauthorized access to identification information resources by an interested party, significantly increases the noise immunity of the identification system as a whole.