ISAR imaging method and device for discrete frequency coding waveform and storage medium

Abstract

The invention discloses an ISAR imaging method and device for a discrete frequency coding waveform and a storage medium. The method comprises the steps: circularly transmitting a pulse group comprising a plurality of transmission pulses with different frequency codes; receiving echo signals returned by the response pulse group; performing matched filtering on the echo signals in sequence by using a matched filter; carrying out alignment and registration processing on each echo signal after matched filtering in sequence by using a cross-correlation function; compensating the residual distance error of each echo signal after the alignment and registration processing; and compensating the residual distance error and then carrying out azimuth imaging processing. According to the invention, emission pulses with multiple different frequency codes are cyclically emitted, that is, a random frequency coding waveform is used as the emission waveform of a radar, so that a target sidelobe can be reduced, the dynamic range of an image is enlarged, the problem that weak scattering points are submerged by strong point sidelobes is solved, and the ISAR imaging quality is improved. The method can be widely applied to the technical field of radars.

Description

technical field [0001] The invention relates to the technical field of radar, in particular to an ISAR imaging method, device and storage medium of a discrete frequency coded waveform. Background technique [0002] In the traditional ISAR imaging method, there is a problem that the side lobe of the strong scattering point submerges the weak scattering point nearby. That is to say, in ISAR imaging, due to the scattering characteristics of the target and the special shape of the component, the echo dynamic range of different components may be large. Using a linear frequency modulation signal (LFM), the side lobe of a strong scattering point is extremely easy to overwhelm a weak scattering point target, causing the loss of target information. For traditional linear frequency modulation signal ISAR imaging, by adding a window to the echo (such as Hamming window, Hanning window, etc.) window, etc.) processing to obtain low sidelobe, but the sidelobe near the main lobe is still st...

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Problems solved by technology

[0002] In the traditional ISAR imaging method, there is a problem that the side lobe of the strong scattering point submerges the weak scattering point nearby. That is to say, in ISAR imaging, due to the scattering characteristics of the target and the special shape of the component, the echo dynamic range of different components may be large. Using a linear frequency modulation signal (LFM), the side lobe of a strong scattering point is extremely easy to overwhelm a weak scattering point target, causing the loss of target information. For traditional linear frequency modulation signal ISAR imaging, by adding a window to the echo (such as Hamming window, Hanning window, etc.) window, etc.) processing to obtain low sidelobe, but the sidelobe near the main lobe is still strong (about -30dB), and the windowing of the signal will also cause the main lobe broadening and energy loss of the signal pulse pressure result. Affecting the range resolution of the radar, energy loss, will affect the signal-to-noise ratio of the image, and adding a window to the signal will cause the sidelobe to lose the performance of the signal

Using random frequency hopping signal ISAR imaging, since multiple pulses are used for bandwidth synthesis, it is necessary to process between pulse groups to obtain Doppler results, which will reduce the repetition frequency of pulse signals, affect the Doppler bandwidth, and bring about ISAR The imaging bandwidth decreases in the imaging azimuth direction, and image overlap is easy to occur

Moreover, the bandwidth synthesis needs to accurately estimate the motion parameters of the target, otherwise the phase compensation is insufficient, which will cause errors in the range image synthesis and affect the image quality

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