Prediction of image performance and real-time quality improvement for the SIR-C/X-SAR SRL-1 mission

For the SIR-C/X-SAR (Space Radar Lab-1) mission, launched the 9th of April 94, the expected image performance for selected sites was evaluated before the mission in terms of S/N ratio, radiometric and spatial resolution and ambiguity ratio related to the best suitable radar settings according to the nominal orbit. The software tool, named Performance Estimator (PE), which was used to calculate the parameters for such an image quality prediction is explained in detail. This tool was also used during the mission to be able to recalculate the radar settings such as PRF, Data Window Position (DWP), etc. According to any changes in the timeline to be sure that the sensor was always correctly pointing the desired scenario. Such changes can be caused either by not acceptable deviations of the shuttle from the planned attitude and orbit, or by the insertion of new experiments required by the scientist according to instantaneous appearing special conditions or effects e.g. volcanic eruptions or can be forced by reacting to contingencies. During the mission a further software tool was used to improve the image quality in real-time. This tool, called Performance Analyzer (PA), is also explained in detail. The purpose of this tool is to analyze the quality of the high rate data (off-line) and to assess the quality of the echo profile obtained with the telemetry data (on-Line) in order to allow, if necessary, the Performance engineer to optimize real-time the echo profile