Spectral Properties and Interpolation Error Analysis for Variable Sample Rate Conversion Systems

The problem of variable sample rate conversion (SRC) has received much attention on account of its applications in software defined radios (SDRs) that must support a wide variety of data rates. In this paper, we investigate the spectral properties of variable SRC and focus on the interpolation error obtained using any two interpolation kernels. We show that SRC is a generalization of decimation for both rational and irrational conversion ratios. In addition, a frequency domain expression for the mean-squared interpolation error is derived and simplified. Simulations presented show the degradation effects of using practical piecewise polynomial based interpolants as opposed to the underlying bandlimited sine function for several input signals.