SAR (synthetic aperture radar) real-time imaging method based on frequency modulated continuous wave

Abstract

The invention discloses an SAR (synthetic aperture radar) real-time imaging method based on a frequency modulated continuous wave, and the problem that a conventional method cannot process the real-time echo data of the frequency modulated continuous wave is mainly solved. The SAR real-time imaging method comprises the following realization steps of: carrying out previous wave filtration on initial data; carrying out Doppler center estimation, walking correction and Doppler center translation on the data subjected to the previous wave filtration; carrying out inverse fast Fourier transform (IFFT) on the data subjected to the center translation along a distance direction; carrying out Doppler frequency modulation rate estimation on the data subjected to the IFFT to obtain a frequency modulation rate value; calculating the motion error parameter of a loader according to the frequency modulation rate value; carrying out motion compensation on the data subjected to the previous wave filtration according to the motion error parameter; carrying out the walking correction, the Doppler center translation and bending correction on the data subjected to the motion compensation; carrying outthe frequency modulation rate estimation on the data subjected to the bending correction; and carrying out focusing and imaging on the data along an azimuth direction according to the obtained frequency modulation rate value to obtain an SAR image. The SAR real-time imaging method has the advantage that the SAR imaging resolution is high, and can be applied to the processing of the real-time echodata of the frequency modulated continuous wave.

Description

technical field [0001] The invention belongs to the technical field of radar imaging, in particular to a synthetic aperture radar real-time imaging method based on frequency-modulated continuous waves, which is mainly used for target detection. Background technique [0002] Synthetic Aperture Radar (SAR) is an imaging system in which a moving radar receives echo sequence signals from stationary ground objects. Frequency modulated continuous wave is to continuously transmit signals within a pulse repetition interval, and its energy is distributed throughout the entire pulse repetition period with a duty cycle of 100%. The SAR based on FM continuous wave generally adopts the Dechirp receiving method, that is, the echo signal is mixed with the reference signal to obtain a difference frequency signal, and the frequency of the difference frequency signal reflects the distance information of the target. In 2009, Dr. Liang Yi from Xidian University introduced an improved range-Dop...

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Problems solved by technology

In 2009, Dr. Liang Yi from Xidian University introduced an improved range-Doppler algorithm based on frequency-modulated continuous-wave SAR in his graduation thesis "Frequency Modulation Continuous Wave SAR Signal Processing". Simulation data, no processing of measured data

However, in the actual SAR platform movement process, because the platform is often affected by various factors and fluctuates, the flight path of the carrier aircraft is offset, making the distance between the target, the speed of the carrier aircraft, and the distance between the target and the carrier aircraft There is an error between the angle and other parameters and the preset value

On the other hand, since the parameters of the carrier aircraft are measured by the inertial navigation GPS, the current domestic inertial navigation accuracy is relatively low, resulting in errors between the actual carrier parameter values ​​and the measured carrier parameter values

In the simulation data, since these motion errors cannot be completely preset, if the method of processing simulation data is directly applied to the measured data, due to the existence of motion errors, the target cannot be accurately focused, which will cause problems such as image blur

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