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This paper reports an experimental study aimed at confirming disruptions in the operation of ADS-B receivers. The experimental investigation into disruptions in the operation of ADS-B receivers involved the FlightAware Piaware receiver. Examples of the disrupted performance of ADS-B receivers are given. It was found that the experimentally detected disruptions in the operation of ADS-B receivers could lead to a decrease in the accuracy of determining the coordinates of air objects with the joint use of the radar and multilateration technology. A method for determining the coordinates of an air object by radar with additional use of multilateration technology has been devised. The method involves the following stages: entering initial data, the calculation of distances between the points of reception and the air object, the computation of the inconsistency vector, the calculation of the matrix of partial derivatives taking into consideration the estimates of the coordinates of an air object at the previous iteration, the computation of the correction, the calculation of the refined coordinates of the air object. Unlike those known ones, the improved method for determining the coordinates of an air object by a radar additionally uses multilateration technology. The accuracy of determining the air objects' coordinates by a radar with the additional use of multilateration technology was estimated. It was established that the additional application of multilateration technology would reduce the error in determining the coordinates of an air object by 1.58 to 2.39 times on average, compared to using only an autonomous radar. [ABSTRACT FROM AUTHOR]

General structure of a compensator of a direct penetrating signal in the diversed reception channel was developed. It is advisable to use the antenna and the receiver of the auxiliary diverted reception channel as an auxiliary antenna and an auxiliary channel. To be able to suppress the penetrating signal in the band of the receiving device of the surveillance radar, distance between the antennas should be up to 6 m. In general, the compensator of the penetrating signals should contain an adder in which the signals received by the main channel are added with the signals received by the auxiliary channel and sent through the amplifier with a corresponding complex transmission coefficient. The direct penetration signal compensator features the obligatory condition of adjusting the value of the complex transmission coefficient of the auxiliary channel signal amplifier. The direct penetration signal compensator is digital and uses the direct method of forming weighting coefficients without the use of feedback. To reduce the time of formation of weighting coefficients when using direct methods of calculation of the correlation matrix, the technology of parallel computational processes was used. The quality of operation of the direct penetrating signal suppression system in the diverted reception channel was evaluated. It was established that without the use of suppression of direct penetrating signals, their powerful response at the output of the matched filter mask weak echo signals. When using a direct penetrating signal in the main channel of the compensator, its response at the output of the matched filter is significantly reduced. This makes it possible to observe weak echoes against the background of a strong penetrating signal. The use of the developed direct penetrating signal compensator provides suppression of the direct penetrating signal from 57 dB to 70 dB [ABSTRACT FROM AUTHOR]

This paper reports the assessment of the detection zone of survey radar stations under a mode of single-place location. The detection zone under this mode significantly depends on the properties of the single-position effective surface of air objects scattering. The assessment of the detection zone of survey radar stations under a mode of the distributed location has been performed. It was established that the dimensions of the detection zone of air objects under a mode of the distributed location depend not only on the characteristics of the transmitting and receiving positions but on the system's geometry and the information combining technique as well. It was established that the size and nature of the detection zones of air objects under a mode of distributed reception depend on the distance to the base line and the degree of suppression of the penetrating signal in the receiving position. The detection zone of survey radar stations was estimated when the modes of single-position and distributed location merge. It was established that the shape of an air object detection zone depends on the design features of a particular air object and would take a different form for different types of air objects. However, the general trend to increase the size of the detection zone and reduce the dependence of its shape on the foreshortening of an air object when the merged modes of single-position and distributed reception is inherent in all types of air objects. The quality of using the merging of single-position and distributed reception modes at the pre-defined flight altitude of an air object was assessed. It was established that the application of the non-coherent combination of the single-position and distributed processing channels would increase the size of the detection zone of stealth aircraft objects by at least 30 % compared to the size of the single-position radar detection zone [ABSTRACT FROM AUTHOR]

Objects of different classes are detected in the process of monitoring airspace. The classification of an air object is the process of establishing its belonging to a preassigned class. Classes are automatically determined or set automated. The unambiguous assignment of air objects to a particular class is an actual scientific task. The purpose of the article is to develop a method for verifying software for a fuzzy logical system for classifying air objects. This problem is solved in a fuzzy setting. To solve this problem, an appropriate software verification method has been developed. The method is based on fuzzy colored Petri nets and uses a base of fuzzy productional rules. The structure of the fuzzy network verification model has been developed. The basis of the model is a fuzzy colored Petri net for representing the base of fuzzy production rules for classifying air objects. For the convenience of visualization of the fuzzy network verification model, the interpretation of the elements of the fuzzy colored Petri net is introduced. The analysis of the state space of a fuzzy network verification model reflects all possible markings. The state space allows to obtain the values of the indicators of all the basic properties of the Petri net. The CPN Tools modeling system is used to build and analyze the state space. The full standard report for the fuzzy logical classification system of air objects was obtained from the simulation results. The report fragment with conclusions about the correctness of the model is given. The report contains sections of state space statistics - the number of nodes, arcs and status, indicators of the properties of reversibility, limitation, survivability and fairness of transitions. The method includes five steps. 1. A base of fuzzy production rules is being developed. 2. The set of interpretation rules transforms the base of fuzzy production rules into the form of fuzzy colored Petri nets. 3. The model is examined for proper functioning. 4. When an error is detected, its type is analyzed. After its correction, the program repeats, starting with any of stages 1, 2 or 3. 5. Reports on the total space of states with various combinations of source data are issued. A final report is issued after analyzing the correctness of the set of reports and correcting errors that have occurred.