Filter System And Method Of Designing A Convolutional Filter

A filter system for filtering an input signal comprises a network of Prism filters including at least one cosine Prism filter and at least one sine Prism filter. The network comprises a first branch (210) in parallel with a second branch, (220) each branch arranged to receive the input signal as an input, the first branch comprising the cosine Prism filter/s (211), the second branch comprising the sine Prism filter/s (221). The network of Prism filters is arranged to generate an output signal based on a combination of an output of the first branch with an output of the second branch. A method of designing a convolutional filter is also provided, comprising inputting a test signal into a filter system to generate an impulse response of the filter system and generating a convolutional filter based on the impulse response.