This paper outlines the development of a new SIR-C processor to replace the original processing system, which is no longer functional. It is important to be able to process raw SIR-C data, because there are several applications for which these data can be used. Two exemplary applications are provided in this paper. First, SIR-C data received with two along-track antennas are used to validate the so-called orthogonal projection algorithm with spaceborne data. Additionally, changes in urban development and infrastructure between the SeaSat and SIR-C missions are analyzed by comparing SAR images of the two radar systems.