DEMETER卫星观测的ULF电场波形干扰分析

Typical interferences of ULF electric field waveform data observed by DEMETER

分析由法国DEMETER卫星观测的ULF电场波形数据,发现两种典型干扰:由标定信号引起的脉冲式周期干扰及详查期间噪声水平增加。结果表明:1周期干扰特征表现为:在固定工作模式期间,干扰以约4 min周期出现;在详查和巡查模式开始时刻,干扰出现。结合VLF频段功率谱,可确认此干扰由625 Hz标定信号引起;2在详查模式期间噪声增加,获取ULF频段功率谱发现,此干扰并非来自单个频点或频段信号,对空间真实的ULF扰动分析影响不大。认识ULF电场波形数据的典型干扰特征,可为后续ULF电场扰动研究提供参考,为我国电磁监测试验卫星同类数据干扰分析提供借鉴。

This paper analyzes typical interferences of ULF waveform records based on ULF electric field waveform data observed by French DEMETER satellite. There are two kinds of typical interferences, regularly impulsive interference induced by calibration sequences and increased noise level during Burst mode. The time features of regular interferences show that regular interferences are observed every 4 minutes inside a mode and at the beginning of each Burst and Survey modes. Combined with VLF power spectra, we can confirm that this kind of interferences is caused by 625 Hz calibration signals. By obtaining ULF power spectra,it is found that the increased noise level of ULF waveform records during Burst mode is not generated by signals of single frequency or band. This type of ULF interferences does not much affect the analysis of real ULF disturbances in space. Understanding typical interferences of ULF electric field waveform data can provide references for future studies on the earthquake-related ULF disturbances based on ULF waveform data observed by DEMETER satellite and the interferences analysis of similar data recorded by China Seismo-electromagnetic Satellite （CSES）.