Retro-regression residual remediation for spectral/signal identification

A processor readable medium storing instructions that, when executed by a processor, cause the processor to:

• a. compute a residual error between an estimated spectrum and a measured spectrum taken of a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques, wherein the estimated spectrum is derived from a mixing coefficients for members of a library spectra that are produced by computing a regression on the measured spectrum with the library spectra;
• b. identify peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum;
• c. perform a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients;
• d. compute corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration;
• e. repeat (a) through (d) with the corrected mixing coefficients computed in (d) being used to generate a new estimated spectrum for computing the residual error in (a) at the next iteration;
• and
• f. determine whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum.

A system for spectroscopic analysis comprising:

• a. a sensor that produces data from a sample of a solid, liquid or gas substance to be analyzed using spectroscopy techniques;
• and
• b. a processor coupled to the sensor, wherein the processor is programmed to:
• i. generate a measured spectrum from the data produced by the sensor;
• ii. perform a regression of the measured spectrum with a library spectra;
• iii. generate estimated mixing coefficients from the regression;
• iv. compute a residual error between an estimated spectrum generated from the estimated mixing coefficients and the measured spectrum;
• v. identify peaks in the residual error that extend in a direction opposite to that of peaks in the measured spectrum;
• vi. perform a regression on the peaks in the residual error that extend in a direction opposite to that of the peaks in the measured spectrum to produce retro-regression coefficients;
• vii. compute corrected mixing coefficients based on the retro-regression coefficients by subtracting the retro-regression coefficients from the mixing coefficients for the estimated spectrum for a current iteration;
• viii. repeat (iv) through (vii) with the corrected mixing coefficients computed in (vii) being used to generate a new estimated spectrum for computing the residual error in (iv) at the next iteration;
• and
• ix. determine whether a chemical or biological constituent whose spectra is contained in said library spectra is present in said sample based on said new estimated spectrum.