Enhancement of Raman Spectra Obtained at Low Signal-To-Noise Ratios: Matched Filtering and Adaptive Peak Detection

Abstract

Two methods of Raman spectral peak enhancement are described. The matched-filter approach employs an optimal filter to maximize the signal-to-noise ratio at its output. The impulse response of the matched filter is the reversed version of the profile of the spectral peak to be enhanced; therefore, the effectiveness of the matched filter depends on a priori knowledge of the peak's shape. The adaptive peak detector (APD) utilizes a filter having a time-varying impulse response. APD performance is relatively insensitive to peak shape, but is instead contingent on a number of user-specified parameters. Background is provided to acquaint the reader with signal processing terminology, and practical guidelines are given for computationally inexpensive computer implementations of both techniques. Examples are shown which demonstrate the effects of these two enhancement methods on simulated Raman spectra.