Centre De Recherche Industrielle Du Quebec

Andre Leblanc

Roger Garceau

Chon T Le Dinh

Le Dinh Tam

A multiple frequency adaptive filter system for filtering undesired periodic and/or correlated interference signals contained in the same frequency band as a desired input signal. The filter system is capable of filtering at least two sinusoidal interference signals and incorporates a negative feedback loop having a transfer function of that of narrow band-pass multiple filter. The feedback loop using interference frequencies generates a corresponding interference enhanced output signal. This enhanced output signal is combined with the input signal whereby to produce an error signal which corresponds to the desired signal contained in the input frequency band. A double or quadruple filter system is also described as examples of the present invention. The filter system is suitable for removing modulated sinusoidal interference and particularly for reducing TV co-channel interference.

Multiple frequency adaptive noise filter for removing interference

The invention relates to an adaptive filtering system for cancelling one or more sinusoidal interference signal contained with a desired signal in an incoming signal. A phase-locked loop is used to track a sinusoidal interference frequency and to synthesize various synchronous in-phase/in-quadrature square wave signals. Each of these signals is weighted in accordance with variations in the amplitude and the phase of the sinusoidal interference signal and the weighted square wave signals are combined together with the incoming signal so as to deliver the desired signal substantially free from any sinusoidal interference signal. In the case of multiple correlated signals, the instant filtering system gives a steady state performance substantially better than that of the well known Widrow-Hoff adaptive notch filter.

Growing community of inventors

Laval, Canada

Andre Leblanc