Data processing algorithms for on-board satellite event analysis

The authors describe the data analysis and reduction schemes employed by the data processing unit (DPU) supporting the magnetospheric ion composition spectrometer sensor aboard the CRRES satellite. One method of reducing output telemetry requirements is to partition the underlying event parameter spaces into disjoint classes, and to downlink statistics based on these classes rather than individual events. The DPUs utilize a hardware implemented binary search algorithm to classify each valid event into one of several mass and mass per charge-state groups, using lookup tables written under software control. The tables contain discrete approximation to polynomial curves which separate adjacent groups. The curves were derived from extensive preflight sensor calibration data using a novel curve-fitting and extrapolation algorithm combining local and global least-squares approximations. Both the onboard table writing software and the techniques employed to derive the boundary curves are described