SEMISYS is the Sensor Meta Information System of the German Research Centre for Geosciences.
The precise analysis of GNSS observation data is based upon a variety of metadata from different sources, including station and satellite metadata. A high evaluation quality must be ensured by the consistency and integrity of this metadata. The station and satellite metadata are currently maintained in ASCII based files that make the extraction of key information used for the data evaluation difficult. To get rid of the restrictions caused by the file based metadata management, the Operational Data Center (ODC) group of the GFZ developed a Sensor Meta Information System (semisys) for the central, format independent and validated storage of station and satellite metadata based upon client/server technology and an object-relational database.
The following processing related metadata is currently stored in semisys:
- Station metadata extracted from IGS site logs (for different projects)
- Processed station coordinates (EPOS) and ocean loading values (calculated by Onsala Space Observatory)
- Hardware metadata (receiver, antenna, radome)
- Satellite parameter for GPS, GLONASS, Galileo, BeiDou, QZSS and SBAS
- Notice Advisories for GPS, GLONASS and Galileo (NANU, NAGU)
- ANTEX for GPS, GLONASS and Galileo
