RU-2861407-C1 - METHOD FOR RADAR DETECTION OF AERIAL OBJECTS IN RADAR WITH PULSE-TO-PULSE FREQUENCY AGILITY

Abstract

FIELD: radar systems. SUBSTANCE: invention relates to controlling the operating modes of radar systems and is intended for selecting and setting parameters of sounding signals with pulse-to-pulse carrier frequency agility in a radar in order to optimise the processing of reflected signals when detecting aerial objects (AOs). In the claimed method, based on the known limitation on the angular correlation time of signals from the AO, as well as the limitation on the minimum pulse repetition period, the main parameters of sounding signals with frequency agility are determined using a control system based on calculation results in the processor of the radar computer. The control of these parameters is necessary for the formation of informative range profiles of AOs with the rational use of the computing resources of the radar computer for detecting AOs in various modes, including under conditions of active and passive interference of artificial and natural origin. EFFECT: development of a method for radar detection of aerial objects in a radar with pulse-to-pulse frequency agility. 1 cl, 3 dwg, 1 tbl

Inventors

• Mitrofanov Dmitrij Gennadevich
• Vitsukaev Andrej Vasilevich
• Filimonova Alena Alekseevna
• Poisov Dmitrij Aleksandrovich

Dates

Publication Date

20260505

Application Date

20250731

Claims (1)

1. A method for radar detection of aerial objects in a pulse-frequency-agile radar, which consists in the fact that the main parameters of frequency-agile probing signals are set in the radar using a control system, which include the duration of the probing pulse τ and , the pulse repetition period T imin , the frequency tuning range ΔF, the number of frequencies used N and the tuning step Δf, characterized in that, based on the value of the minimum permissible pulse repetition period T imin for the pulse-to-pulse frequency tuning mode, using the processor of the electronic computer of the radar control system, the number N of repetition periods is calculated, which fit within the range of angular correlation time T uk of signals reflected from aerial objects, amounting to T uk = 5 ms, according to the formula N = T uk /T imin , taking into account the maximum possible longitudinal size of the aerial object R || max , subject to detection and servicing by the radar, using the processor of the electronic computer, the size R N of the viewing window is calculated portraits by range according to the formula R N = 2R || max , taking into account the size of the viewing window R N , using the processor of the electronic computer, the value of the intervals between readings in the formed range portrait is calculated according to the formula δR = R N /N, based on the value of the intervals δR between readings, using the processor of the electronic computer, the required range ΔF of frequency tuning is calculated according to the formula ΔF = c / (2δR), where c is the speed of propagation of electromagnetic waves, as well as the frequency tuning step according to the formula Δf = ΔF / N, using the processor of the electronic computer, the duration τ and of the radar pulse in the carrier frequency tuning mode are calculated according to the formula τ and = R N /c.

Description

The invention relates to the control of operating modes of radar systems and is intended for selecting parameters of probing signals with the tuning of the carrier frequency from pulse to pulse in the interests of optimizing the processing of reflected signals when detecting airborne objects (AO). It is known that when designing radar systems, the duration τ and the ultra-high frequency probing pulse are chosen to be as small as possible to increase the standard resolution ΔD in range (ΔD=cτ and /2, where c is the propagation speed of radio waves), but as large as possible to ensure the required power of the emitted signal in the interests of increasing the range of the radar [1-3]. It is also important to consider that the spatial pulse width τ should be commensurate with the effective dimensions of aerial objects, reaching 50 meters or more. At τ = 1 μs, the spatial pulse width is 300 m, and at τ = 0.5 μs, the spatial pulse width is 150 m. With such durations, any aerial object is smaller in size than the spatial pulse width, and all the energy reflected from it is processed, ensuring the required detection rates. This is why most radars have a pulse width of τ and at least one microsecond. It is known [4] that in the mode of selection of moving targets, as well as in the normal mode when tuning the frequency from pulse to pulse, the choice of the pulse duration τ is made only taking into account a sufficient spatial extent. In this case, the detection zone shown in Fig. 1 is divided (the region of space around the radar, limited in range by the near and far boundaries of the detection zone, in which, in the absence of intentional interference, the detection of air objects is ensured with a probability not lower than the specified one) into B = 2π/Θ β azimuthal sectors, where Θ β is the width of the antenna directivity characteristic in the azimuthal plane, and range strobes, where R B and R D are the ranges to the near and far boundaries of the detection zone, the range where d is the range strobe number It is proposed to select the d-th range strobe as the reference range. The range strobes have a duration of τ and a length of cτ and , but overlap with each other by cτ and /2 to prevent the splitting of reflections from the VO into parts when the VO is located on the boundary of adjacent strobes. Within each range strobe, reflected signals at N different frequencies are received, processed in matched filters, amplified, and stored in the memory of an electronic computer (EC), forming the frequency response (FR) of reflections in this strobe. Each pulse in a frequency-tuned burst has its own frequency, different from the others, within the tuning range ΔF. The carrier frequency does not change within a pulse. The frequency tuning step Δf depends on the number N of pulses in the burst: Δf≈ΔF/N. The inverse Fourier transform (IFT) of the frequency response results in the formation of an impulse response (IR) [5]. Multiplying the time values of the IR elements by the propagation velocity of radio waves (c≈3 × 10 8 m/s) transforms the impulse response into a range portrait (RP) of reflections belonging to the corresponding range strobe. The procedure for forming the impulse response or range portrait is described in detail in [5], where it is shown that the RP is a set of responses, each of which has an amplitude proportional to the intensity of reflection from the corresponding scattering center (SC), and a position on the range axis corresponding to the distance of the SC relative to the radar (reference range). As an option in [5], the recommended pulse duration in the carrier frequency tuning mode is 1 μs. Thus, according to the accepted implementation of frequency-variable signals (FVS) using the OPF method, a DP of duration R N = δR×N is formed, where N is the number of frequencies used in the FVS packet, ΔR is the linear distance or interval between adjacent elements (samples) in the FVS, and where ΔF is the frequency tuning range. The range resolution ΔR is equal to twice the interval between readings in the DP, i.e. ΔR=2δR. The time resolution Δt in the impulse response is inversely proportional to the tuning range. and the time interval δt between readings in the IH is two times smaller The parameters of a modern radar are controlled by a control system, which includes a computer. The names of such systems in radars of different purposes may differ (onboard computing system, synchronization and control system, automated control system, central processor, etc.). Depending on the operating mode of the radar, the control system determines with its control signals the values of the main parameters, which include pulse durations, carrier frequencies, pulse repetition periods, frequency tuning range, the number of pulses in the SFC packet, the frequency tuning law, etc. With an arbitrary choice of pulse duration, the number of pulses in the SFC packet, as well as the frequency tuning range ΔF, the length