Interferometric SAR processor for elevation

An interferometric synthetic aperture radar system for three-dimensional imaging of a target area, comprising:

• a carriage moving along a motion track in said target area;
• an electromagnetic pulse generator disposed on said carriage, sequentially producing and transmitting coherent electromagnetic pulsed signals to said target area, said generator and carriage operating to allow spatial overlap of two illuminated areas of two sequentially transmitted pulses;
• two electromagnetic signal receivers attached to said carriage and spatially displaced from each other, detecting scattered pulsed signals of said coherent transmitted pulsed signals from said target area;
• an analog-to-digital converter capable of transforming analog signals into digital form;
• a data storing device for retaining digital signals;
• a positioning device, providing attitude, velocity and position information of said carriage and thereby said signal receivers;
• an electronic processor, operating to process said signals in digital form for a three dimensional electronic image of said target area based on a coherence property of said signals;
• a first signal processing mechanism in said processor, enabling said processor to encode said attitude, position and velocity information of said receivers to said signals, forming a first data channel and a second data channel corresponding to said two receivers, respectively;
• a second signal processing mechanism in said processor, enabling said processor to obtain spatial frequency information of said signals in both an azimuth direction along said motion track and in a range direction from said carriage to said target area, to sequentially divide received data into a series of patches at a predetermined resolution with any two adjacent patches having partial overlap with each other, and to perform 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 detected by said receivers;
• a third signal processing mechanism in said processor, enabling said processor to align said first data channel and said second data channel with respect to a common reference, to perform a motion compensation process to project both channels onto said reference, resulting a range shift and a phase shift for both said channels;
• said third signal processing mechanism operating to enable said processor to carry out a resampling procedure to interpolate said data at said shifted range value and apply said phase shift to signal values in said first and said second channels and to apply 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;
• a fourth signal processing mechanism in said processor, enabling said processor to apply a second correlation process to each said data channels in said azimuth direction relative to said reference based on a second information indicative of a property of said pulses, said velocity information of said carriage, and relative positioning of said receivers with respect to said target;
• said fourth signal processing mechanism further enabling said processor to produce an interferogram by correlating said first data channel with said second data channel;
• a phase unwrapping mechanism in said processor, enabling said processor to perform a phase-bootstrapping procedure in which phase information of a overlapped region of two adjacent data patches are used for correlating phase values of said two adjacent patches, and to determine relative phase values of every data point in a patch that is bootstrapped by said phase-bootstrapping process;
• a phase resolving mechanism in said processor, enabling said processor to cross correlate a first subset of data of said interferogram with a second sub set of data thereof and thereby to determine a absolute phase value of said interferogram directly relating to a difference between a first range from said target area to said first receiver and a second range from said target area to said second receiver;
• and
• an imaging mechanism in said processor, producing said three dimensional image by having said processor to correlate each pixel in said interferogram with said position information from said positioning device.