Abstract—The paper studies the influence of signal quantization levels number on accuracy of the results of spectral analysis. The overflow effect (signal threshold clipping due to shortage of the quantizing device bits) is also considered. A formula is derived for transforming a real number to its nearest quantization level. Numerical modeling of the quantized realizations of harmonic signal (pure one and mixed with noise) as well as its Fourier transform’s basis functions is performed to construct characteristics – dependencies between programassigned signal parameters and those measured in the course of digital processing under various quantization and clipping conditions.