Communications: directive radio wave systems and devices (e.g. – Synthetic aperture radar
Patent
1993-07-29
1994-08-30
Hellner, Mark
Communications: directive radio wave systems and devices (e.g.,
Synthetic aperture radar
342195, G01S 1390
Patent
active
053432045
ABSTRACT:
Inverse synthetic aperture radar imaging systems that are used to image targets that undergo rotational accelerations are enhanced by signal processing techniques which provide correction factors to reduce the frequency-shift and frequency-stretch errors that occur due to such accelerations. A target scan is subdivided into a number of sub-apertures and a Fast Fourier Transfer (FFT) is performed on the data for each sub-aperture to provide associated frequency sub-images. The FFT is then subdivided in "sub-swaths" of amplitude versus frequency for a plurality of frequency bands. The change-of-frequency, or frequency shift, data between prominent scattering points of each sub-image are processed to provide a phase correction factor that incorporates range changes and translational acceleration distortions for additional scattering points other than the most prominent scattering point. A frequency-stretch correction factor that compensates for rotational acceleration distortion is also provided.
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Farmer Michael E.
Hatlestad John D.
Bowen Glenn W.
Hellner Mark
Starr Mark T.
Unisys Corporation
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