Multiangle Spectropolarimetric Imager (MSPI) Onboard Processing: In-flight Algorithm Validation and Data Reduction

Looking ahead to a spaceborne instrument, where decreased data rates for downlink become a high priority, we have implemented a real-time parametric extraction algorithm for MSPI that runs on a Xilinx Virtex-5 FXT FPGA. The processor analyzes oversampled polarimetric image data and produces an estimate of the linear components (I, Q, U) of the associated Stokes vector. We have flown the processor on an ER-2 and validated the real-time results against post-processed data. To further reduce downlink requirements, we combine the Stokes parameters to degree/angle of linear polarization and perform 2x2 spatio-temporal averaging. The final result is a 2-order-of-magnitude reduction in the data rate.