Characterization of S-Band SAR Data as a Precursor to NISAR

This paper summarizes the characterization and experience of S-band SAR data acquired using NovaSAR mission which can be considered as a precursor to NISAR calibration and validation. As NISAR is an up-coming challenging mission which has capability to operate in L and S bands and with multiple polarizations, it is high time to comprehend and establish the methodology pertaining to calibration and validation of ISRO’s S-band SAR payload and its data products. In this paper, the design and deployment strategy of corner reflectors employed for NovaSAR at ISRO’s Operational Cal-Val site at IMGEOS along with methodology adopted for deriving image quality parameters are presented. Based on the analysis, it can be inferred that the deployed corner reflectors for NovaSAR are suitable for the calibration and validation of NISAR S-Band SAR sensor. Derivation of Radiometric quality parameters viz radiometric resolution, Speckle Index, Equivalent Number of Looks, Noise Equivalent Sigma Zero and Gamma0 profiles on homogenous regions were also discussed and derived parameters are meeting the specifications. The radiometric and geometric calibration and validation results achieved by performing point target and distributed target analysis on NovaSAR data along with the expertise gained in estimating the relevant parameters will be an indispensable assert for NISAR.