To make the phase difference of a radar image surely fall within a reference value and to make acquirable an image having a high reproducing accuracy by continuing the phase compensating process until a phase-compensated phase error converges within a reference value.
An image reproducing processor 3 reproduces a compasited aperture radar image by using an echo signal amplified by a broad-band transmitter-receiver 1, Fourier-transforms the image by an azimuth FFT unit 4 in an azimuthal direction to obtain a spectrum Spcf. The spectrum is equally divided by a spectrum divider 5 by an order N, inverse Fourier-transformed by an azimuth IFFT unit 6 to obtain N pieces of images. Then, arbitrary two images selected by an image correlator 7 are mutually correlated to calculate the moving amount Δ of the image. A phase compensator 8 calculates a coefficient δ of the phase error from the amount Δ to phase-compensate the image, and an image reproducer 9 reproduces the radar image. Here, a convergence judging unit 11 designates the continuity of a phase compensating process if the phase error after the phase compensation does not converge within the reference value or judges its convergence if it converges within the reference value to finish the process.
IWAMOTO MASAFUMI
KIRIMOTO TETSUO
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