Filtering > a second order MA filter

Digital filters can operate in the space domain by using the convolution product. A sampled signal can be represented by a polynomial of variable z and/or by a set of coefficients. The convolution product of two signals is the product of the polynomials in z domain of these signals. All linear filters can be presented by the relationship between two polynomials in z. A filter for which the polynomial is a fraction, whose denominator is equal to 1, is a moving average filter or MA. In this section, we study the behaviour of a second order MA filter. The second order MA filter is a Notch filter used to attenuate industrial currents in seismic acquisition.