Bramanti M., Marchesini E. Analysis of a PLL system as analog processor in CW doppler flowmeters. In: IEEE Transactions on Biomedical Engineering, vol. BME- pp. 584 - 589. IEEE, 1983. |

Abstract (English) |
In this paper a piliase-Iocked loop (PLL) system is analyzed in order to evaluate its performance for estimating the average frequency of an input spectrum made up by N discrete components allocated in a frequency interval B. The system was studied first in the simplified case that the phase comparator has a linear characteristic. Next, a computer-aided simulation of the PLL system was performed taking into account the nonlinear characteristic of the phase comparator, assuming that me input spectral components have mutual random phase in (-π, +π) interval and amplitudes with a distribution either uniform or obtained from a particular parabolic velocity profiles. The obtained results show that the estimate given by a PLL system differs from the true average frequency value for a negligible percent error. It is also shown that me PLL estimate is generally better than the zero-crossing detector estimate. | |

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