| A conventional SAR (Synthetic Aperture Radar) processor reconstructs an image of the Earth's surface from radar echoes. Under some circumstances, the Fourier spectrum of the image is more useful than the image itself. A special purpose DCSS (Direct Complex SAR Spectrum) Processor is presented in this thesis to fulfill the needs of obtaining an image spectrum without explicitly forming the image. Such an approach is more efficient in the sense that it reduces the complexity of obtaining the spectrum than through conventional procedures. The DCSS processor preserves phase information of the image within its spectrum. This aspect of DCSS processor is important to certain advanced SAR applications, where the phase information is critical.;This thesis presents in detail the methodology of DCSS processing, along with its software implementation. Test runs on the DCSS software have been conducted, and the results are reported. The principles behind conventional SAR image reconstruction are reviewed. A particular SAR processor, PHPSP (Phase Preserving SAR Processor), made available by the Canadian Centre for Remote Sensing (CCRS) is used to produce complex images (ie. with amplitude and phase), which are then transformed into the wavenumber domain. Resulting spectra are compared to those obtained via the DCSS processor.;While the present DCSS processor is able to generate two-dimensional complex image spectra in a manner which preserves phase information, some deterioration of image fidelity has been detected. This is believed to be caused by an approximation employed in the DCSS processor, and can be reduced via suitable post processing techniques.;This thesis is a proof-of-concept exercise in DCSS development. As such, its scope is restricted to dealing with simulated, range-compressed echoes pertaining to airborne SAR specifications. |
