Multifunctional GNSS-R Processing Software FOR GNOS II

Global Navigation Satellite System-Reflectometry (GNSS-R) is a remote-sensing technique for Earth surface observation. Global Navigation Satellite System Occultation Sounder (GNOS) II is an instrument, developed by National Space Science Center (NSSC), which can perform both GNSS radio occultation (RO) and GNSS-R. The GNSS-R module of GNOS II is capable of generating real-time Delay-Doppler mapping (DDM) for measuring wind speed over sea. Besides this basic scientific function, GNOS II can also record raw IF data for further study on reflection signal's feature and improvement on instrument's algorithm. To process the raw data collected by GNOS II, an off-line data processing software called multifunctional GNSS-R processing software (MRPS) has been developed. MRPS is mainly designed for processing raw data recorded by GNOS II to generate DDM synchronized with real-time DDM, and it can also process raw data collected by general GNSS recorder. Before converting raw data into DDM samples, MRPS first evaluates the quality of recorded signal. Then conventional GNSS-R (cGNSS-R) technique is applied to generate DDM. And a re-tracking algorithm is realized to compensate for the misalignment between DDM samples. This software has been used to process simulation data and airborne data collected by GNOS II and will be used to process spaceborne data in the future.