Design of efficient digital interpolation filters for integer upsampling

Abstract

Digital signal interpolation systems can be implemented in a variety of ways. The most basic interpolation system for integer upsampling cascades an expander unit with an interpolation low-pass filter. More complex implementations can cascade multiple expander and low-pass filter pairs. There is also flexibility in the design of interpolation filters. This thesis explores how digital interpolation systems for integer upsampling can be efficiently implemented. Efficiency is measured in terms of the number of multiplications required for each output sample point. The following factors are studied for their effect on system efficiency: the decomposition of an interpolation system into multiple cascaded stages, the use of recursive and non-recursive interpolation filters, and the use of linear-phase and minimum-phase interpolation filters. In this thesis interpolation systems are designed to test these factors, and their computational costs are calculated. From this data, conclusions are drawn about efficient designs of interpolation systems for integer upsampling.