Method of linear filtering
AssigneeANT Nachrichtentechnik GmbH
InventorThomas Harbich
Life of this patent
Estimating the term…
Abstract
A nonrecursive digital filter, particularly for filtering signals wherein identical values frequently occur in succession. The problem of making such a filter fully integratable at low expense is solved in that the time of a change in signal state with respect to a reference point in time is stored, with these points in time being utilized to address a further memory in which the system specific step response of the filter is stored. These step responses are weighted in a computer with the amplitude associated with each change in signal state, and are accumulated with the proper sign so that the accumulated output signal of the computer represents the desired filtered signal.
Claims9
A method of filtering an input signal by a nonrecursive linear digital filter including the steps of:
- (a) providing an addressable memory in which the filter system specific step response of the filter is stored;
- (b) detecting each change in amplitude of said input signal;
- (c) for each detected change in amplitude, setting one counter of several counters, associated with each respective said change in amplitude, to a starting value and increasing the value by a constant amount at regular time intervals so that the respective counter states represent the time intervals between changes in signal amplitude relative to a reference point in time in units of one clock pulse period;
- (d) utilizing said contour states to address said addressable memory and to cause readout of the addressed said step responses;
- (e) weighting each read out step response with the amplitude of the input signal associated with the respective changes in amplitude;
- (f) accumulating each weighted step response under consideration of its sign in an accumulator, whereby the output signal of the accumulator represents the desired filtered signal;
- and
- (g) repeating step (c) by associating those counters which reach a predetermined counter state corresponding to the time duration of the filter system specific impulse response with subsequently occurring changes in amplitude.
Dependencies are inferred from the claim text.