| 摘要 |
PURPOSE:To eliminate noise components and to improve the accuracy of A/D conversion in an A/D conversion system. CONSTITUTION:The signals which are fetched from a power system 1 through a current transformer 2, a transformer 3 and a filter 4 are sampled by a sampler/holder 5 at each fixed time (DELTAt), and also the sampling data are held for a fixed time. Then the AGE conversion is carried out N times by an A/D converter 6 while the sampling/holding data of a single time is held. Thus N pieces of digital conversion data are obtained. Then these conversion data undergo the spectrum analyses by a digital signal processing circuit 7 and through the fast Fourier transformation (FFT). Thus only the DC component is taken out a single-sample signal is outputted. In such a way, the noise components generated before the A/D conversion undergo the spectrtm analyses through the FFT processing. As a result, the noises are reduced and the accuracy of A/D conversion is improved. |
