Welcome to PCS - Product Control Service.

The Quality Control Philosophy

A remote sensing mission involves several aspects such as the flight-segment operations, the instrument calibration and aging monitoring, the ground station and the processing facility operations and maintenance, the mission management (to ensure the continuity and to improve the mission performances) and last but not least the scientific community requirements. In order to give a high contribution to these different aspects it is essential to develop a mission quality control strategy.

The methodology adopted in the ERS Mission has been to monitor the whole system performances by analyzing the quality of the data produced by the system itself. Based on the mission strategy and the data source, the control of the following elements were considered essential in the process of quality assessment:

• Platform/Instrument operations
• Ground Station acquisition performance
• Raw data availability
• Ground Station processing performance
• Instrument aging monitoring
• Instrument calibration monitoring
• Quality of the delivered data sets
• Compliance of the delivered products with specifications
• Systems upgrades and configuration controls
• Users concerns
• Reporting

Quality control procedures oriented on routine operations (Platform/Instrument) and on fast delivery products are performed in parallel with the data dissemination. This implies that the users who need to apply their own quality rejection criteria can occasionally receive some bad quality data. On the other hand, this concept allows for a quick provision of data less than three hours from sensing, usually of good quality.

Algorithm validation and systems upgrade require off-line procedures. The validation activities of new algorithms, developed during the mission lifetime, require a good capacity to interact with different communities such as the algorithm experts, industry and mission coordination. In addition to this expertise it is essential to have a reference processing station available to tune the processing. Another important element that runs off-line is the back-up station. This allows the reprocessing of large amounts of data when necessary (new algorithm or new set of processing parameters). This element is essential to provide a consistent data set throughout the whole mission.

Instrument performance monitoring (calibration and aging) requires both strategies (on-line, off-line) and a set of procedures that enable to analyze the data (interactively) and to extract periodically statistical parameters into a database, to be used for long-term characterization of the instrument performances. Moreover these activities require a good knowledge of the instrument and its calibration technique. It is also necessary to investigate instrument or platform anomalies and, if feasible, to propose corrective actions to phase out those anomalies and to ensure the continuity of the mission.

User concerns require a series of efforts. In particular it is important to know the users requirements, to explain what is possible or not in the mission scenario and to interact with industry if new solutions shall be integrated to improve the data quality.

The reporting is essential to share the information acquired throughout the quality control procedures. The reporting is a very general concept and covers a wide range of applications. It has a daily or cyclic (35 days) frequency to report the instruments and products performances or it could have the special issue to report about anomalies, mission events, system upgrades or users complaints.

In order to inform users and provide them with a coherent overview of reports, results of analysis, important instrument or mission events and other PCS activities, the PCS has started its own website.

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