1. National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
2. National Space Science Center, Chinese Academy of Sciences, Beijing 100190, China
3. Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
4. Institute of Experimental Physics, Graz University of Technology, 8010 Graz, Austria
5. DFH Satellite Co., Ltd., Beijing 100081, China