M.D. Monakhov1, I.V. Kamenskiy2, K.Yu. Gavrilov3

1–3 Moscow Aviation Institute (National Research University) (Moscow, Russia)

1 maksimusmaks1998@gmail.com, 2 kamenskijiv@mai.ru, 3 gvrk61@mail.ru

The problem of optimal processing of an ultra-wideband signal with step frequency modulation (SFM) for radar sensing of a dispersed medium characterized by the dependence of the attenuation coefficient on frequency is considered. When using the condition of maximizing the value of the signal-to-noise ratio (SNR) as an optimality criterion, an optimal signal processing algorithm based on the maximum likelihood ratio method is obtained.

When probing dense media such as concrete or brick wall, the values of the attenuation coefficient can vary within a few tens of dB per meter with a bandwidth of the SFM-signal of 2...6 GHz. Under these conditions, the optimal processing of the SFM-signal is reduced to the operation of fast Fourier transform (FFT) with the weight summation of discrete samples using an asymmetric window. In this case, the type of the weight window function depends on the dispersed properties of the medium and is selected based on a priori information about the medium. In this paper, the use of the Rayleigh function with the possibility of adjusting the width of the window and the magnitude of the displacement of its maximum relative to the center is proposed for the formation of an asymmetric weight window.

The results of computer simulation are presented, which showed that when the attenuation coefficient changes within 30 dB/m (a concrete wall with low humidity), the proposed algorithm provides an average gain in the value SNR of about 7 dB in comparison with the signal processing algorithm with a symmetrical Hamming window. At the same time, there is a deterioration in the range resolution by 1,1...2 times, the value of which can be adjusted using the Rayleigh window parameter.

The results of field experiments in probing concrete and brick environments are also presented, confirming the validity of theoretical conclusions and the results of computer modeling. Field experiments were carried out using a radar layout using a SFM-signal with a bandwidth of 5,1 GHz and an initial frequency of 900 MHz.

Monakhov M.D., Kamenskiy I.V., Gavrilov K.Yu. Processing of ultra-wideband signals in subsurface sensing radar. Achievements of modern radioelectronics. 2023. V. 77. № 10. P. 57–69. DOI: https://doi.org/10.18127/j20700784-202310-06 [in Russian]

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