SAR is an all-weather remote sensing technique which achieves high resolution and large swath widths. It is rapidly becoming a key technology in remote-sensing applications. SAR uses a short chirped pulse and matched-filter processing to obtain fine range resolution. Fine azimuth resolution which is range-independent is obtained by using the platform motion and coherent processing of Doppler-shifted radar pulses to synthesize a large antenna. Due to environmental disturbance and limitation of the SAR facility and handling techniques

errors

including random errors

system errors or both

would occur in each system node or subprocess of the overall SAR imaging process. These errors may greatly affect the quality of SAR images and lead to the uncertainty in their eventual application. For example

phase error may severely blur and deform SAR images. Image defocusing

radiometric distortion

and increased sidelobe levels hamper target detection and recognition. Geometric distortion prevents direct pixel-to-pixel comparison of SAR images or the matching of SAR with other forms of imagery It is crucial to understand the nature of error and the way they affect the quality of final images through error propagation and synthesis. Generally speaking

the sources of uncertainty in SAR system include the instability of SAR sensor

navigating system

platform motion and its motion compensation

SAR digital imaging process

image process and etc. These error sources could cause phase error

positional error and gray level error which are embedded in the final corrupted image. Currently

processing of gray level error includes radiometric calibration

speckle noise reduction and radiometric enhancement

positional error

handled by geometric coarse correction and geometric fine correction. Presently

the solution of phase error and positional error falls mainly in motion compensation

it is related with the Inertial Navigation System

SAR data driven process

and the combination. The relationships among on phase error

gray level error

and possibly positional error and their synthesis

though important

have not been investigated. Furthermore

the way these errors propagate in terms of mechanism from error sources through the SAR imaging process has seldom been made. A thorough examination of these aspects will prove to be crucial in uncertainty management and quality improvement of SAR images . The purpose of the present study is to make an initial attempt to probe into various sources causing phase error

positional error and gray level error

and to establish a relationship among these errors. We also investigate the mechanism-based propagation of errors along the SAR imaging process

their final synthesis and impact on the quality of SAR images.