Figure 1.

Comparison of energy addition and geometric translation of a signal by noise. In each panel the amplitude is plotted as a function of time and threshold is indicated by a horizontal dotted line. Top Panel: Intrinsic noise ε is plotted on the lowest (green) trace. The sinusoidal wave represents the subthreshold signal h (dark blue). Middle panel: The traces indicate the interaction of h and noise to obtain a noisy signal by energy addition(red) or by geometric translation (light blue). The noisy signal obtained by energy addition (red) does not reach threshold, so the SR would traditionally be classified as Type I. However, if the original subthreshold signal h is translated by the intrinsic noise ε with its mean m, the noisy signal obtained by geometric translation (light blue) is entirely above threshold. Lower Panel: As a result of Steps 1,2 and 3, the "denoised" signal is recovered entirely above threshold.