Elimination of digital and analog artefacts from time-domain signals.

A method is described for the elimination of artefacts that arise in time-domain signals because of the presence of digital and analogous filters. Such artefacts are mostly located at the beginning of the free-induction decay (FID). The procedure introduced here is particularly important if at least one signal component decays rather quickly, i.e. if there is only a small number of data containing this component (as for solid-state 1 H or 2 H FIDs). The method is able to restore the original signal by deconvolution of the spectrometer output from the transfer function of the spectrometer console. The transfer function is connected to the filter characteristics. Experimental estimation of this function is demonstrated. The estimation applies differentiation of the output signal in the case of a step-like input. This kind of input could be realized either by very slowly decaying FID or by digitizer overflow. The results are discussed with respect to the best approximation of original FID.