[PEM11-05] Next generation interplanetary scintillation observation telescope using 2D phased array system
Keywords:Heliosphere, Interplanetary scintillation, phased array, instrument , Radio telescope, coronal mass emissions (CMEs)
There are still many important issues in the heliospheric physics, such as the acceleration and propagation of the solar wind, propagation of coronal mass emissions (CMEs) in the inner heliosphere, the global structure of the heliosphere, and its variations associated with the solar activity. These issues are also important for the space weather forecasting. Interplanetary scintillation (IPS) is a radio scattering phenomenon caused by the disturbances in the solar wind. The IPS observation using ground-based radio telescopes has been an important technique to investigate the global structure of the heliosphere. We, Nagoya University, have observed the solar wind velocity and density irregularities for several decades using our own large radio telescopes at 327 MHz. Recently, the unusual solar actively makes complex solar wind distributions, which requires more detailed IPS observations. Detecting CME structures is also required to forecast the arrival of CMEs. In this study, we investigated the design of next generation IPS observation instruments, and developed their pathfinders.
Multi-point IPS observations throughout the year are required for more detailed reconstructions of the solar wind velocity distributions. In order to realize the IPS observation even in the snowfall season, we considered a flat two-dimensional phased array with a wide field of view. This structure is also resistant to natural disasters such as typhoons by eliminating the drive unit. The real time digital signal processing of the receiver system is required for the digital multi beam forming that observes multiple directions simultaneously. This system will enable us to take several all-sky IPS maps within a day to track fast CMEs. This system is also able to detect the passage of CMEs and derive their structures by tracking a specific radio source. One of the important development parts in this project will be the digital signal processing part that requires about 1000 units of digital boards. We designed and developed a low-cost digital board dedicated to the IPS observation using ADCs and FPGAs, and found that the digital board has enough performance. The developed prototype is able to process 8 signals simultaneously and has a size of 37cm x 27cm, which is a reasonable size for the mass-production.
Multi-point IPS observations throughout the year are required for more detailed reconstructions of the solar wind velocity distributions. In order to realize the IPS observation even in the snowfall season, we considered a flat two-dimensional phased array with a wide field of view. This structure is also resistant to natural disasters such as typhoons by eliminating the drive unit. The real time digital signal processing of the receiver system is required for the digital multi beam forming that observes multiple directions simultaneously. This system will enable us to take several all-sky IPS maps within a day to track fast CMEs. This system is also able to detect the passage of CMEs and derive their structures by tracking a specific radio source. One of the important development parts in this project will be the digital signal processing part that requires about 1000 units of digital boards. We designed and developed a low-cost digital board dedicated to the IPS observation using ADCs and FPGAs, and found that the digital board has enough performance. The developed prototype is able to process 8 signals simultaneously and has a size of 37cm x 27cm, which is a reasonable size for the mass-production.