Focusing SAR images formed by RMA with arbitrary orientation
AssigneeRaytheon Company
InventorKwang M. Cho
Life of this patent
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Abstract
A system and method (44) for focusing an image oriented in an arbitrary direction when the collected synthetic aperture radar (SAR) data is processed using range migration algorithm (RMA). In accordance with the teachings of the present invention, first (60) the data is skewed so that the direction of smearing in the image is aligned with one of the spatial frequency axes of the image. In the illustrative embodiment, the smearing is aligned in the vertical direction. This is done through a phase adjustment that was derived from the requirements for proper shift in the spatial frequency domain. Next (62), the signal support areas from all targets are aligned by proper phase adjustment in the spatial (or image) domain. Finally (64), the common phase error can be corrected using autofocus algorithms.
Claims24
A system for focusing an image oriented in an arbitrary direction collected by a synthetic aperture radar (SAR) system with multiple targets having corresponding signal support areas comprising:
- first means for skewing said image;
- second means for aligning said signal support areas from all targets after said image has been skewed;
- and
- third means for correcting common phase error after said signal support areas have been aligned.
A system for focusing an image oriented in an arbitrary direction collected by a synthetic aperture radar (SAR) system with multiple targets having corresponding signal support areas comprising:
- an antenna for transmitting and receiving electromagnetic energy;
- a transmitter for sending transmit information to said antenna;
- a receiver for processing said received electromagnetic energy;
- and
- a signal processor with a range migration algorithm containing a phase correction system adapted to execute:
- a first function for skewing the image data;
- a second function for aligning the signal support areas from all targets after the data has been skewed;
- and
- a third function for correcting common phase error after said signal support areas have been aligned.
A method for focusing an image oriented in an arbitrary direction collected by a synthetic aperture radar (SAR) system with multiple targets having corresponding signal support areas including the steps of:
- skewing said image;
- aligning said signal support areas from all targets after said image has been skewed;
- and
- correcting common phase error after said signal support areas have been aligned.
Dependencies are inferred from the claim text.