An Introduction of GNSS Reflectometer Remote Sensing Mission From Yunyao Aerospace Technology Co., Ltd.

Global Navigation Satellite System (GNSS) Reflectometry (GNSS-R) is the use and study of GNSS signals’ distortion and delay reflected or scattered by the earth’s surface to tell us the sea level, wind speed and direction, humidity, ice density, and even moving targets. The space-borne GNSS-Reflectometer from Tianjin Yunyao Aerospace Technology Co., Ltd. is China’s first commercial GNSS-R instrument. On July 3, 2021, this payload was equipped on the Jilin-1 wide-range 01B satellite (J1-01B) developed by Changguang Satellite Technology Co., Ltd. and entered the polar orbit with the height about 500km from the Taiyuan Satellite Launch Center.The attitude of J1-01B is stable to the ground within 0.1 degrees, which can guarantee the high accuracy of GNSS-R antenna gain model on the detection of sea surface wind speed and direction, soil moisture and etc. Meanwhile, its orbital characteristics ensure that its trajectory can cover the north and south poles of the earth, providing opportunities for researches on sea-ice detection and sea-ice thickness retrieval. The payload supports the mutual switching between dual system (GPS L1 or BDS B1) signal mode and dual working mode (generate the doppler delay maps (DDM) in manual-adjustable resolution on the satellite, or collect intermediate frequency (IF) data with 58Mb/s rate), which guarantees the verification and continuous development of multi-system compatibility, data quality analysis and application scenario expansion.After two weeks of satellite’s launch, the satellite has entered normal working mode. In two periods from 6:0 to 6:15 and from 7:32 to 7:42 on July 16, 2021, GNSS-R data were collected in DDMs as well as IFs formats, when J1-01B was over the Pacific Ocean. And L1a DDMs with the horseshoe shape were generated with correction from raw DDMs, as well as from IFs.The GNSS-R instrument on the Jilin-1 wide 01B satellite is an important component of the Yunyao constellation plan, which would provide rich and stable data, and be an important role in global and regional exploration in aerospace, meteorology, ocean, earthquake and other fields.