Boots – shoes – and leggings
Patent
1995-12-18
1998-02-24
Trammell, James P.
Boots, shoes, and leggings
364487, 364483, 364570, 364576, 341123, 324 55, G01R 2310, H03M 100
Patent
active
057216894
ABSTRACT:
A method and system for estimating phasors and tracking the frequency of a signal is provided. The method uses a variable N-point DFT to compute one or more phasors based on data acquired from one or more sampled signals. At each sampling interval the change in phasor angle between the current sampling interval and the previous sampling interval is determined and used to estimate the instantaneous frequency of the signal. Instantaneous frequencies are averaged over a cycle of the signal. In addition, a number of discrete frequencies and corresponding DFT windows based on a fixed sampling rate and a predetermined fundamental frequency of the signal are defined and used in estimating the instantaneous frequency. Once the average cycle frequency is determined the DFT window is adjusted by setting it equal to the DFT window corresponding to the discrete frequency closest to the average cycle frequency.
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Hart David
Hu Yi
Novosel Damir
Smith Robert
ABB Power T&D Company Inc.
Nguyen Cuong H.
Trammell James P.
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