M.F. Volobuev1, V.N. Nadtochiy2, V.S. Kostennikov3

1–3 J MTSC Air Forces «MAA named professor N.E. Zhukovsky and Y.A. Gagarin» (Voronezh, Russia)

1 volmf81@mail.ru, 2 nadtochiy_90@mail.ru, 3 vitaly.kostennickov@yandex.ru

Modern receivers of multifunctional airborne radar stations of dual-purpose air-craft operate in dynamically changing parameters of the useful signal and noise. The parametric uncertainty of noise is a consequence of a change in antenna resistance, a change in the path of propagation of an electro-magnetic wave due to unstable climatic conditions and cosmic radiation, as well as a change in the thermal noise of the receiver of an on-board radar station. This uncertainty leads to a decrease in the efficiency of the receiver of the on-board radio location station, which consists in reducing the probability of correct detection or increasing the probability of a false alarm. The greatest decrease in the efficiency of on-board radar receivers is manifested with a small signal-to-noise ratio due to a large distance to the detected object, or the effects of interference.

Improving the efficiency of on-board radar receivers with a low signal-to-noise ratio and its ability to make a decision on the presence or absence of a signal in a minimum time is an urgent research task.

Currently, various approaches are being used to improve the efficiency of on-board radar receivers. The most common is to increase the signal-to-noise ratio by increasing the power of the probing signal. This approach is difficult to implement in most air-borne radar stations, since their operation is carried out at potentially achievable power. The second approach is based on the development of new methods for detecting radio signals, the main of which are adaptive.

In adaptive methods, the uncertainty of the statistical characteristics of the received signal and noise realization is overcome by evaluating them based on experimental data and then using the information obtained to optimize the parameters of the on-board radar receiver. When the probability of a false alarm acts as an optimized parameter, the noise level is estimated based on the obtained statistics of the distribution of a random variable, on the basis of which the threshold is adjusted. The disadvantages of these methods are a long time to ensure convergence to optimal solutions, sensitivity to erroneous calculations, high computational costs, which leads to inefficient operation of on-board radar receivers.

Existing adaptive detection methods use optimal detection criteria, according to which the decision on the presence of a radio signal is made using trigger decision functions after exceeding the threshold value. Increasing the efficiency of the considered detection methods in conditions of a small signal-to–noise ratio and changes in noise parameters is possible using another class - non-trigger solving functions, for example, piecewise linear.

The aim of the work is to develop a method for optimizing the parameters of the piecewise linear decision function of the receiver of the on-board radar station of a dual-purpose aircraft, depending on the noise intensity.

The results of solving this problem are a new method for detecting radio signals, new analytical expressions for calculating the threshold value and the adaptable slope angle of a piecewise linear decision function, provided that radio signals with a random phase and random initial phase and amplitude are received. The dependences of the probability of correct detection of radio signals on time at the initial stage of operation of the onboard radar station are investigated.

The graphs show a comparison of the time characteristics of the classical approach to adapting a receiver with a system for stabilizing the level of false alarms and the developed method, with the possibility of adapting the parameters of the receiver of an on-board radar station by changing the angle of inclination of the piece-wise linear decision function.

Volobuev M.F., Nadtochiy V.N., Kostennikov V.S. Method for detecting radio signals based on optimization parameters of non-trigger crucial functions of the on-board radar receiver. Achievements of modern radioelectronics. 2024. V. 78. № 3. P. 50–58. DOI: https://doi.org/10.18127/j20700784-202403-06 [in Russian]

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