Piece-wise linear DFT interpolation for IIR systems: Performance and error bound computation

In this paper, a method is proposed in order to provide an upper bound on the error obtained by approximating a discrete-time system by a finite impulse response, in case of having no a-priori information about the original system other than given frequency response samples. The method uses a first-order frequency-domain approximation for the reconstruction of inter-sample frequency response, leading to fast upper bound calculation. The bound gives useful information about the error magnitude in applications where system blocks are implemented using fast Fourier transform techniques, specially in robust control systems.