SIGNAL-TO-NOISE RATIO ENHANCEMENT IN FREQUENCY-MODULATION SPECTROMETERS BY DIGITAL SIGNAL-PROCESSING

A signal-to-noise ratio enhancement of an order of magnitude was obser ved when digital signal-processing algorithms were applied to two diod e-laser frequency-modulation spectrometers in the near-infrared and mi dinfrared spectral ranges. These algorithms include digital bandpass f ilters, a Wiener filter, a matched filter, and a least-squares fit. Di gital signal processing has a practical advantage over other noise sup pression techniques because it is easy to implement and to adapt to al l experiment configurations without any physical modifications or addi tions to the spectrometer.