A method for accurate full spectrum testing without requiring coherency

Achieving coherent sampling to accurately estimate the spectral characteristics of a signal is a very challenging task. Though the Four point sine wave fitting method can be used to accurately estimate some spectral parameters of a non-coherently sampled signal, not all parameters can be estimated accurately. This paper proposes a method that can be used to accurately estimate ALL the spectral characteristics from the spectrum when a signal is not sampled coherently. The non-coherent fundamental and harmonics are accurately identified and replaced with their corresponding coherent signals to achieve accurate results. Simulation results show the effectiveness and robustness of the method.