High-accuracy interpolator design with reduced first-order derivative constraints.

In this article, we propose a new frequency-domain weighted-least-squares method for designing high-accuracy interpolator (interpolation kernel) that reduces the number of the first-order derivative continuity constraints. By reducing the number of the first-order derivative constraints, we can increase the degree of freedom in the design, and thus have more flexibility to get more accurate design results. The interpolator consists of 6 piecewise polynomials of the third degree (cubic), and it is performed in the frequency-domain through minimising the weighted integrated-squared-error of the spectrum (frequency response). The weighting function is adjusted so as to ignore some insignificant frequency bands and put more emphasis on the important frequency bands. By imposing the continuity constraints on the interpolator itself as well as the reduced first-order derivative constraints at the contacting points, we get three free parameters of the interpolator. These three parameters are then optimised in such a way that the weighted integrated-squared-error of the frequency response is minimised. We will utilise a narrow-band example to demonstrate the performance improvement over other existing interpolators. [ABSTRACT FROM AUTHOR]