Abstract
This paper deals with the amplitude estimation in the frequency domain of
low-level sine waves, i.e. sine waves spanning a small number of
quantization steps of an analog-to-digital converter. This is a quite
common condition for high-speed low-resolution converters. A digitized
sine wave is transformed into the frequency domain through the discrete
Fourier transform. The error in the amplitude estimate is treated as a
random variable since the offset and the phase of the sine wave are
usually unknown. Therefore, the estimate is characterized by its standard
deviation. The proposed model evaluates properly such a standard deviation
by treating the quantization with a Fourier series approach. On the other
hand, it is shown that the conventional noise model of quantization would
lead to a large underestimation of the error standard deviation. The
effects of measurement parameters, such as the number of samples and a
kind of the time window, are also investigated. Finally, a threshold for
the additive noise is provided as the boundary for validity of the two
quantization models
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