An encoder spectrograph is used to analyze radiation from one or more
samples in various configurations. The radiation is analyzed by spatially
modulating the radiation after it has been dispersed by wavelength or
imaged along a line. Dual encoder spectrographs may be used to encode
radiation using a single modulator. A spectra sorting algorithm is used
to determine calibration training spectra for a spectrometer in a
spectrometer calibration training mode.