Analysis of Ionospheric Delay Gradients of Multi-GNSSs Using GIM and Klobuchar model over Thailand region

การวิเคราะห์ค่าเกร์เดียนต์เวลาหน่วงชั้นไอโอโนสเฟียร์ของ GNSS หลายระบบโดยอาศัยค่า GIM และแบบจำลองโคลบุชาเหนือพื้นที่ประเทศไทย


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#Digital Technology
การวิเคราะห์ค่าเกร์เดียนต์เวลาหน่วงชั้นไอโอโนสเฟียร์ของ GNSS หลายระบบโดยอาศัยค่า GIM และแบบจำลองโคลบุชาเหนือพื้นที่ประเทศไทย


This research proposes an ionospheric delay gradient (IDG) estimation method to detect the anomalous gradients of multi-GNSSs (i.e., GPS, GLONASS, and Galileo) over Thailand region. We employ the Klobuchar model and Global Ionospheric Maps (GIMs) for estimating the slant total electron content (STEC) values, the corresponding gradients amide the aforementioned GNSS is estimated using the base receiver and real-time kinematic (RTK) drone data. The results show that the estimated STEC values in the GIMs overestimate the corresponding values from the Klobuchar model, which suggests a possible variation in their estimated gradients. This study shows that this kind of gradient variation cannot represent a perfect correlation due to the limited accuracy of Klobuchar model estimates. Moreover, the ionospheric gradient values estimated by GPS satellites are also higher than the GLONASS and Galileo constellation of satellite signals. This event occurred due to the difference between the two successive positions of the flying rover, which were highly precisely estimated by GPS satellites compared to GLONASS and Galileo observations. The outcomes from this study underline the benefits of multi-GNSS processing for mitigating the ionospheric gradients for relative improvement in precise positioning under varied ionospheric conditions.


The ionospheric delay gradients (IDG) not only affect directly to the positioning accuracy of advanced technology, but also has the high impact on navigation and landing of aircraft. Hence, the IDG should be detected to identify the ionospheric irregularity event such as plasma bubble. Hence, this research has an idea to propose a method to estimate the IDG and use this operation as a precursor for navigation business and positioning enhancement of advanced technology.

Project Members

ปุณยวีร์ จามจรีกุลกาญจน์
Punyawi Jamjareegulgarn


ภาคิน จิ้นจ้าย



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