The optical current transformer is an important content in smart grid research field. When the Faraday DC optical measurement system was used in DC current measurement, the low frequency noise caused by photo detector and measured signal were overlapped, which makes the measuring accuracy decrease. To solve this problem, the noise of photo detector is analyzed. Then, the frequency modulation is proposed for spectrum shifting. Furthermore, the principle of modulation method is deduced in formula, and the characteristics of deferent frequency are also analyzed. On this base, modulation signal source is designed. With LabVIEW program, the signal from modulation source is acquainted and analyzed. The results show that this modulation method can realize spectrum shifting and the designed signal source is able to generate waveform needed.
Characteristic Analysis of a Difference-Based Cascade Thermocouple Measurement System in Steady Flow
