K.Yu. Gavrilov1, E.V. Kudryashova2, O.V. Malysheva3

1 MAI (NRU) (Moscow, Russia)

2,3 PJSC NPO “Almaz” (Moscow, Russia)

The problem of determining the coherence interval of the target (CIT) is considered – the time interval during which the signal reflected from the target can be considered coherent. In this case, the criterion of signal coherence is the condition of limiting the random phase fluctuation of the reflected signal to a value. The basis of the method of determining the CIT is the use of a multipoint model of a target that performs a rectilinear motion at a constant speed. When describing the resulting signal, the complex envelope method is used.

It is shown that for an arbitrary number of reflection points, the resulting signal can be represented as a product of two functions. The first function is deterministic and determines the dependence of the signal phase on the speed of movement of the target center. The second function determines the amplitude and phase fluctuations of the reflected signal and, due to the unknown number and location of the reflection points, as well as the angle of observation of the target, can be considered random.

In the case of a two-point target model, an approximate ratio for the CIT is obtained, depending on the relative size of the target, its range and speed of movement. It is shown that for typical target sizes and ranges of the order of several tens of kilometers, the errors in calculating the CIT when using the obtained approximate ratio do not exceed 10% of the true value of the CIT. It is also shown that the frequently used approach of calculating the CIT based on the calculation of the backscattering diagram of the target does not take into account the target range and therefore can lead to large errors in calculating the CIT. At the same time, the calculated values of the CIT, depending on the size of the target and its range, may differ from the true values by an order of magnitude or more.

When switching to the multipoint model of the target, differences in comparison with the two-point model in the calculation of the CIT are determined and estimates of the most rational number of reflection points are obtained, the choice of which can be limited to five or six points.

Gavrilov K.Yu., Kudryashova E.V., Malysheva O.V. Determination of the coherence interval of radar targets using a multipoint signal reflection model. Radiotekhnika. 2023. V. 87. № 7. P. 77−88. DOI: https://doi.org/10.18127/j00338486-202307-09 (In Russian)

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