A faster method for accurate spectral testing without requiring coherent sampling

The Discrete Fourier Transform (DFT) is the ubiquitous method of choice for spectral testing. Nevertheless, the correct application of DFT for slightly distorted sinusoidal signals requires either strict coherent sampling, or careful windowing, or other methods that are not computationally efficient. This paper introduces an improved method for achieving accurate spectral testing for approximate sinusoidal signals without the need for coherent sampling or windowing. Theoretical analysis, simulation and experimental results show that the proposed method is faster than the original method and more robust when the signal frequency is close to Nyquist frequency. Comparative studies demonstrate that the proposed algorithm achieves better spectral testing accuracies than those obtained using the windowing techniques.