In studying image formation methods of the spaceborne synthetic aperture radar (SAR), we utilize its modeling and
simulation (M&S) to generate its realistic simulated rawdata. Especially, for the spaceborne spotlight SAR, we perform
M&S that reflects its real characteristics, and get rawdata that are almost identical to one acquired by the real SAR
Particularly, operations of the spaceborne spotlight SAR are simulated based on models of its dynamics and geometry
related to timeline, orbital state vector, antenna beam pattern, azimuth beam steering, and etc. In addition, the target
observation of it is modeled as evaluating observation angles related to point targets within the acquisition time. Finally,
based on the received echo signal model, rawdata are simulated for point targets taking into account its real operation.
For the high resolution SAR image formation, simulated rawdata are focused with the extended chirp scaling algorithm.
Especially, its range cell migration (RCM) factor is the key one for the exact range cell migration correction. In order to
do it accurately, the Doppler frequency and the effective velocity have to be calculated correctly for all range sample
bins. For precise processing, we suggest the method to analyze them using orbital state vectors and scene coordinates
based on two way slant range model.
In experiments, system parameters and imaging scenarios to simulate rawdata acquisition of the spaceborne spotlight
SAR system are defined. The processing results for realistic simulated rawdata of it are presented to evaluate the
performance and the effectiveness of proposed methods. Its results show that suggested methods are applicable to form
the high resolution spaceborne spotlight SAR image.