A signal preprocessing algorithm applicable to both DTF and SSME spectral diagnostics

An account is given of research conducted by NASA-Stennis' Diagnostic Test Facility (DTF), which is designed to obtain spectra approximating those of the SSME while allowing full control of dopant and thruster conditions. A simple preprocessing technique which emphasizes the essential spectral components of plume spectra that are indicative of dopant levels has been used and found to remain sensitive to wavelength shift even for high-resolution spectra. Mathematical analyses of the problem are presented which are based on the Taylor's series linearization procedure.