On nonlinear filters involving transformation of the time variable
Douglas J. Moore, David Parker · IEEE Transactions on Information Theory · 1973
A new type of nonlinear filter, called theE-filter, is introduced that involves a transformation of the independent variable of the input function. It is shown how anE-filter can be designed to filter out superimposed "noise" on a signal, leaving the large peaks of the signal unattenuated. Unlike a Iow-pass linear filter, the low-passE-filter is almost frequency independent and so does not affect the amplitudes of large sharp peaks of the signal. It is shown that theE-filter can be realized in real time and that a wide class ofE-filters have a filtering action which is independent of the dc level of the input signal.