Abstract: A method and apparatus for comb filtering a PAL type television signal is described. Preferably, the television signal is digitized by sampling it at an even multiple of its chroma subcarrier frequency, thereby to convert the television signal to a series of digital signals representative of discrete picture elements. The value of each such digital signal is indicative of the value of the luminance component and the value of the amplitude and phase of the chroma component of its associated picture element. The phase of the chroma component of a reference picture element is changed by combining and averaging stored digital signals associated with selected picture elements whose chroma component is of the desired phase and which, in combination, cancel out luminance components.

Abstract: A recursive digital filter is disclosed for removing noise from an incoming television signal. The filter couples the incoming television signal to a subtracter without substantial attenuation of the television signal. The subtracter also receives at an input an attenuated difference signal comprising a selected amplitude of the difference between the incoming signal and an earlier received signal which has been delayed for an interval corresponding to one television frame. The subtracter subtracts the attenuated difference signal from the incoming signal and develops an output in which noise is substantially reduced.