Automated estimation of white Gaussian noise level in a spectrum with or without spike noise using a spectral shifting technique

TitleAutomated estimation of white Gaussian noise level in a spectrum with or without spike noise using a spectral shifting technique
Publication TypeJournal Article
Year of Publication2006
AuthorsSchulze, H. G., M. M. L. Yu, C. J. Addison, M. W. Blades, and R. F. B. Turner
JournalApplied Spectroscopy
Volume60
Pagination820–825
ISSN0003-7028
Abstract

Various tasks, for example, the determination of signal-to-noise ratios, require the estimation of noise levels in a spectrum. This is generally accomplished by calculating the standard deviation of manually chosen points in a region of the spectrum that has a flat baseline and is otherwise devoid of artifacts and signal peaks. However, an automated procedure has the advantage of being faster and operator-independent. In principle, automated noise estimation in a single spectrum can be carried out by taking that spectrum, shifting a copy thereof by one channel, and subtracting the shifted spectrum from the original spectrum. This leads to an addition of independent noise and a reduction of slowly varying features such as baselines and signal peaks; hence, noise can be more readily determined from the difference spectrum. We demonstrate this technique and a spike-discrimination variant on white Gaussian noise, in the presence and absence of spike noise, and show that highly accurate results can be obtained on a series of simulated Raman spectra and consistent results obtained on real-world Raman spectra. Furthermore, the method can be easily adapted to accommodate heteroscedastic noise.

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