The Imaging Algorithm Of Missile-borne Spotlight Mode SAR

Synthetic aperture radar is a high resolution imaging system which is using microwave remote sensing imaging technology. It can obtain the two-dimensional imaging of range and azimuth. As a kind of active radar, its launch the electromagnetic wave and achieve the imaging effect is far more than infrared. It also almost not affected by the natural environment such as cloud and fog. So it can obtain high resolution radar images and not affected by the weather and environment outside all day. Now the SAR imaging technology is already widely used in airborne and space-borne platform. But its application on the missile-borne platform is not particularly adult. The application of SAR technology in missile, will greatly improve the operational capability of missile and the ability of radar on target recognition under the complex battlefield environment, so the SAR technology of missile-borne has become a hotspot of current radar research. And the characteristics of SAR working in spotlight mode is small scene and high resolution imaging, just accord with the requirement of missile target accurately, in view of this, this thesis carried out the Imaging algorithm research of missile-borne spotlight mode SAR, The main contents are as following:I was studied the RD imaging algorithm of level flight missile-borne spotlight mode SAR, and give out the level flight missile-borne spotlight mode SAR’s imaging geometric model, and analyzed the missile-borne spotlight SAR’s echo signal characteristics, deduced the RD algorithm that is suitable spotlight mode imaging. using Taylor series expansion the instantaneous slant range, ignore high-order item that more than 4 order, and got the approximate expressions, then convert the echo signal expression to the two-dimensional frequency domain conducted range compression, secondary range compression, range curvature and higher-order migration correction, Finally validates the effectiveness of the algorithm through the simulation test, laid the foundation for the further algorithm research.I was studied the PFA imaging algorithm of dive trajectory missile-borne spotlight mode SAR, on the basis of dive trajectory missile-borne spotlight mode SAR’s geometric model, analysis the characteristics of the echo signal. Using the reversion of the series method derivation the two-dimensional spectrum expression, and corrected related parameters in the two dimensional spectrum, finally got the SAR images.I was studied the improved PFA imaging algorithm on the period of dive trajectory and curve avoid phase, using the instantaneous slant range between platform and the center of the scene of geometric model of spotlight mode as the reference distance, Correction of the doppler center deviation. Using the reversion of the series method derivation the two-dimensional spectrum expression, then decoupling, range compression, azimuth compression and image position correction, eventually get the ideal SAR images. This method only use the FFT/IFFT and phase multiply operation, not using the complex operations such as interpolation in original algorithm, greatly reduce the amount of calculation and improve the running speed of the algorithm, is conducive to real-time imaging.On the basis of the further study of missile-borne SAR imaging algorithm, using the methods that Matcom software associated with MATLAB and VC programming, completed the missile-borne SAR imaging simulation software design.