Question

(a) What are two software methods of signal to noise ratio enhancement? (b) Briefly explain how one of them works. Describe how signal to noise ratio affects LOD concentration.

Answer 1

1) Digital Filtering. overused fourier transform

2) Ensemble Averaging. Also called coaddition.

FOURIER TRANSFORM FOR TREATMENT OF SIGNAL/ NOISE:  A Fourier transform is a way to decompose a signal into a sum of sine waves. The amplitude and phase associated with each sine wave is known as the spectrum of a signal. If the spectrum of the noise if away from the spectrum of the original signal, then original signal can be filtered by taking a Fourier transform, filtering the Fourier transform, then using the inverse Fourier transform to reconstruct the signal.

LOD concentrations and noise

Low concentrations of a component, will have in any method of instrumental analysis, low intensity. If the signal/noise ratio is low, exist a high noise in the measumerent process, so it is likely that the signal of analytes at low concentrations is not perceived, representing LOD higher. This situation of high noises, represents a major problem in trace analysis, because the noise hides the analyte signal.