Vibration error compensation method for helicopter-borne rotation type synthetic aperture radar

Abstract

The invention discloses a vibration error compensation method for helicopter-borne rotation type synthetic aperture radar, and belongs to the technical field of radar signal processing. The method mainly comprises the steps that a helicopter and rotation type synthetic aperture radar are determined, a geometric model of the helicopter-borne rotation type synthetic aperture radar is built, a pointtarget P is determined, the actual slant range course between the rotation type synthetic aperture radar and the point target P is obtained, and then echo signal data of the point target P is calculated; according to the echo signal data of the point target P, a two-dimensional spectrum of the point target P is obtained; according to the two-dimensional spectrum of the point target P, a point target P with vibration error distance-Doppler signal is obtained; according to the point target P with vibration error distance-Doppler signal, a signal obtained after phase error compensation is obtained; according to the signal obtained after phase error compensation, a final focusing signal is obtained, wherein the final focusing signal is the vibration error compensation method result of the helicopter-borne rotation type synthetic aperture radar.

Description

technical field [0001] The invention belongs to the technical field of radar signal processing, and in particular relates to a vibration error compensation method of a helicopter-borne rotary synthetic aperture radar, which is suitable for improving the imaging quality of the rotary synthetic aperture radar and obtaining a precisely focused image. Background technique [0002] Rotary Synthetic Aperture Radar (ROSAR) is a radar antenna that is added to the helicopter rotor blade or rigid bracket, and the synthetic aperture is obtained by rotating the helicopter blade; compared with the traditional linear SAR, ROSAR further simplifies the antenna structure; In practical applications, there are still many limitations that have not been solved; the biggest problem is the compensation of the motion platform error; for the application of ROSAR, the helicopter is the main platform. Uniform load; at the same time, the interaction between the blade and the air will generate vibration...

AI Technical Summary

Problems solved by technology

[0002] Rotating Synthetic Aperture Radar (ROSAR) is to add a radar antenna to the helicopter rotor blade or rigid bracket, and obtain the synthetic aperture through the rotation of the helicopter blade; compared with the traditional linear SAR, ROSAR further simplifies the antenna structure; but in In practical applications, there are still many limiting problems that have not been resolved; the biggest problem is the compensation of the motion platform error; for the application of ROSAR, the helicopter is the main platform, and during the flight, the rotor blades of the helicopter bear the heavy load. Uniform load; at the same time, the interaction between the blade and the air will generate vibration and spread to the entire motion platform, further aggravating the amplitude of vibration

This vibration will cause paired echoes at the target point, causing image quality degradation

[0003] Due to the periodic time-varying and time-frequency characteristics of the vibration of the helicopter, it will be difficult to compensate the vibration error through an accurate analytical method when the vibration parameters are unknown; the traditional imaging algorithm rarely considers the vibration error on the slant distance history , the frequency histories of the paired echoes and the synthetic slope range histories caused by the unique ROSAR imaging mode cannot usually be deduced, which also increases the difficulty of analytical derivation of the phase error; Analysis and research on the vibration error caused by the existence of the frequency history; therefore, for the traditional imaging algorithm of error compensation, the self-focusing method cannot be directly applied to eliminate the vibration error

[0004] In order to solve this problem, according to the characteristics of platform vibration, a parameter estimation method of sinusoidal frequency modulation signal based on adaptive chirp wavelet decomposition technology has been proposed in the literature, but this algorithm has been based on the vibration phase error analysis of non-spatial distance variation formula, there is no suitable algorithm in the existing literature to solve ROSAR vibration error compensation

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