초록 ▼

An interferometric Synthetic Aperture Radar (SAR) system having a special-purpose processor to integrate motion compensation, interferogram coregistration, and a spectral shifting for optimal interferogram correlation together to achieve efficient, accurate, and robust three-dimensional imaging. A s

An interferometric Synthetic Aperture Radar (SAR) system having a special-purpose processor to integrate motion compensation, interferogram coregistration, and a spectral shifting for optimal interferogram correlation together to achieve efficient, accurate, and robust three-dimensional imaging. A simple radar mapping coordinate system is implemented in the present invention to enhance the overall image processing and in particular to improve the accuracy and efficiency. The present invention substantially improves the fidelity and efficiency of phase unwrapping by incorporating phase-bootstrapping process, a correlation filter, and other processes. Absolute phase determination is implemented without known ground references by two proposed techniques employing cross-correlation of sub-patches to generate a number of estimates within a patch and weighting correlation processes.

대표청구항 ▼

An interferometric method for generating a three dimensional image of a target, comprising: transmitting coherent electromagnetic probing pulses to said target by using at least one coherent electromagnetic pulse generator, allowing spatial overlap of two illuminated areas upon said target by two se

An interferometric method for generating a three dimensional image of a target, comprising: transmitting coherent electromagnetic probing pulses to said target by using at least one coherent electromagnetic pulse generator, allowing spatial overlap of two illuminated areas upon said target by two sequentially transmitted pulses; providing a moving carriage and two signal receivers attached to said moving carriage, said receivers being spatially displaced relative to each other and operating to detect electromagnetic signals; detecting scattered electromagnetic pulses from said target illuminated by said probing waves by using said receivers on said moving carriage; transforming analog signals of said detected scattered pulses from said receivers to digital signals, forming a first data channel and a second data channel corresponding to said two receivers, respectively; employing at least one positioning device to obtain attitude, position and velocity information of said moving carriage and thereby attitude, position and velocity information of said receivers; sequentially dividing received data into a series of patches at a predetermined resolution with any two adjacent patches having partial overlap with each other; performing a first correlation process on each of said two data channels in a range direction from said carriage to said target based on a first information indicative of a property of said pulses generated by said generator; aligning said two data channels relative to each other and in particular to a pre-determined spacing in a reference coordinate system within which said data channels are processed; including Doppler effect in squinted observations in said aligning process using said position and velocity information from said positioning device; performing a motion compensation process to project both channels onto a local reference motion track in said reference coordinate system, resulting a range shift and thereby a phase shift for both said channels; carrying out a resampling procedure to interpolate said data at said shifted range value and apply said phase shift to each data point in said first and said second channels; applying a range migration procedure to both said first and said second channels to adjust a dependence of range on positioning of said carriage with respect to said target by applying a second correlation process to each said data channels in an azimuth direction parallel to said motion track based on a second information indicative of properties of said pulses from said receivers and said attitude information of said receivers; performing a multiplication of said first data channel with a complex conjugate of said second data channel and thereby producing an interferogram of said two channels; performing a phase unwrapping process to determine relative phase values of every data point in a patch; carrying out one of an absolute phase determination process to an unwrapped patch to directly relate said phase of said patch to a range difference from said receivers to said target or a phase-bootstrapping procedure in which phase information of an overlapped region of two adjacent data patches are used for correlating phase values of said two adjacent patches; and producing a three-dimensional image of said target by further processing said interferogram using said position and velocity information from said positioning devices.