Space Technology Applications Network

The Radiometric Calibration of Satellite Sensors Project

The project is aimed for coherent and collaborative access to the Network of Satellite Sensors Calibration Sites, in addition to the current LANDNET Sites in TuzGölü, Turkey, and Dunhuang, China, which can be shared by all APSCO Member States and validated for use in radiometric calibration. It is also aimed to improving the capacity of APSCO Member States to accomplish the radiometric calibration of optical and microwave, active as well as passive, satellite sensors. This will be accomplished through a combination of training and field campaign events, as well as joint research to improve understanding of the state-of-the-art in radiometric calibration methodologies. Also, further develop APSCO resources required for radiometric calibration needs, both for today and into the future.

The Project was approved as a Basic Activity by the Ninth Council Meeting in 2015, and TUBITAK UZAY of Turkey is playing the leading role in the project implementation. The Joint Working Group comprising of two experts from each Member State has been formed. The Project was officially kicked off in August 2017, back-to-back with an in-class training and field campaign activity. The training topics covered Basic Principle, Pre-Launch Radiometric Calibration, On-Board Radiometric Calibration, Absolute Radiometric Calibration, Cross Calibration and Absolute Calibration. During the Field Campaign, the participants from all APSCO Member States had a unique opportunity to access and learn by practice at the LANDNET Gobi Site and Vegetation Site in Dunhuang, China. In August 2018, the 2nd training and field campaign were held and focused on more advanced topics including radiometric calibration of SAR satellite sensors. Another LANDNET Site in our APSCO Member State, TuzGölü Site in Turkey, was used as the main venue for the event. With these capacity-building activities, APSCO Member States have gained teams of trained and experienced personnel in the area of radiometric calibration.

In order to increase the opportunities for absolute radiometric calibration within APSCO, new site expedition and evaluation activities will be carried out in other Member States in the third year of the implementation. Meanwhile, in order to keep accumulating best practices and know-how in radiometric calibration, organization of trainings, field campaigns and workshops will be continuously organized throughout the course. Also, collaboration and resource-sharing under the auspices of an APSCO Center of Excellence in Radiometric Calibration is envisioned to facilitate longer-term collaboration.

There are many other areas of applications from space technology, apart from remote sensing, that can help improving quality of life on Earth. Communication and GNSS satellite technologies, for instance, profoundly influence activities in our daily living. In order to improve quality of the satellite service, as well as to promote utilization of space technology for wider range of application, APSCO has grouped its cooperative projects under the network of space technology application. Currently, there are a number of applications and research projects, both basic and optional activities, initiated by our Member States.

➢ Research on Atmospheric Effects on Ka-Band Rain Attenuation Modeling Project

The feasibility study of the Research on Atmospheric Effects on Ka-Band Rain Attenuation Modeling Project was approved to implement as a Basic Activity by the Sixth Council Meeting of APSCO in 2012. It aims to establish a database from collected Ka-Band beacon signals and related meteorological data. Then the best practices for understanding of rain process and its related atmospheric effects concerning signal attenuation for Ka-Band satellite communication can be investigated. Finally, the Rain Attenuation Model and Diversity Site Switching Algorithm are among the final goals of this project.

The project was officially kicked off in 2014. After that, the implementation of the Project had been running smoothly under the leadership of Thailand. It passed the Preliminary Design Review and Critical Design Review milestones in 2014 and 2015, respectively. Its Test Demonstration Review on the database of collected Ka-Band beacon signals and related meteorological data was conducted in 2016. New proposed regional Rain Attenuation Model and Diversity Site Switching Algorithm were also evaluated. With more data collected and analyzed, the models and algorithms optimized and verified, the Project was successfully closed out in 2017 with very fruitful outcomes. The developed algorithms and models were warmly welcomed in the international community, and presented at some world-recognized forums, such as International Astronautical Congress (IAC) and IEEE International Conference on Communications (ICC). The optimized regional rain attenuation model as well the physical consistency verification methodology expected to be addressed to the Working Group of the International Telecommunication Union (ITU) for adoption. The outcomes in form of project deliverables have been shared among APSCO Member States.

➢ Ionosphere Modeling through Study of Radio Wave Propagation and Solar Activity Project

The project was approved by the Ninth Council Meeting of APSCO, in 2015, as an Optional Activity. Bangladesh, China, Mongolia, Pakistan, Peru and Thailand participate in the project, under the leading role of China Research Institute of Radio Wave Propagation (CRIRP). The project aims to establish and evaluate ionospheric models in the Asia-Pacific region through the study of radio wave propagation and solar activity. It is also to provide cooperative mission of ionospheric related research to APSCO Member States.

The project was kicked-off in May, 2016. The TEC/Scintillation sounding equipment’s have been successfully installed in the participating Member States. Under the framework of this optional activity, the Ionosonde equipment’s have also been installed in Pakistan, in 2017. With the full deployment of monitoring receivers in all participating Member States, the Ionospheric Monitoring Network would be established under which all participating Member States would be capable of carrying on the joint research based on fully shared sounding data.

➢ International GNSS Monitoring and Assessment (IGMA)

Compatibility and interoperability of navigation signal is the main characteristic of modern GNSS development and applications. The IGMA project was proposed by China to carry out monitoring and assessment of GNSS open services that can improve the quality of service and enhance the reliability of service. The project was included into the Development Plan of Space Activities of APSCO in 2011. Its main aims are to build GNSS data collection points in all Member States, set up a data analysis system and carry out monitoring and assessment procedure for GNSS service performance and ionospheric delay modeling. This would help APSCO Member States to better understand the service performances of major satellite navigation systems, including GPS, BD, GLONASS, and Galileo, in their countries. It can enhance the capacity of our Member States in the satellite navigation system area, especially on data processing and analysis and to promote the application of satellite navigation technology among APSCO Member States.

The feasibility study of the project was approved by the Ninth Council Meeting in 2015 for implementation under the framework of Basic Activity of APSCO. The kickoff meeting of the project was organized in October, 2016. As the first step of the implementation, the hosting site survey activities have been carried out to ensure the physical and environmental conditions of the proposed stations in Member States meet the requirements defined in the Site-Hosting Requirements and Procedures given by the project lead. After the survey, the work plan for site improvement were discussed and drafted between the project lead and the host country. The IGMA equipments are now being installed at the verified hosting sites in APSCO Member States. Once fully established, the network would be open for all APSCO Member States for carrying on the joint research based on fully shared data policy.

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