Nominal ionospheric delay gradient estimation at Suvarnabhumi airport, Thailand

Budtho, Jirapoom; Supnithi, Pornchai; Saito, Susumu; Saekow, Apitep

doi:10.1109/ieecon.2017.8075859

Cited by 2 publications

(3 citation statements)

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“…From 2013 to 2016, the averages of σ Vig are about 5 mm/km. In the related works, Budtho et al () measured the nominal ionospheric delay gradients during 2015 in the Thailand area and Saito, Yoshihara, et al () measured ionospheric delay gradients from 2011 in the Japan area, σ Vig values on quiet days showing they are about 5.27 and 4.9 mm/km respectively, which are comparable to the nighttime estimation in this work. The range of the σ Vig estimation is around 4.5 to 6.5 mm/km, except on the 62nd day in 2013, when there is only one day within the four‐year period with σ Vig of about 8.5 mm/km.…”

Section: Resultsmentioning

confidence: 99%

“…According to the transformation matrix, when the integer ambiguity of the first satellite is questionable, this error will affect the others and causes such failure. For this reason, the first satellite elimination (Budtho et al, ) is applied whenever the faults occur. Then the LAMBDA method chooses the new candidates and processes all the remaining steps again.…”

Section: Methodsmentioning

confidence: 99%

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Analysis of Quiet Time Vertical Ionospheric Delay Gradients Around Suvarnabhumi Airport, Thailand

2018

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Global Navigation Satellite System (GNSS) is vital to aircraft navigation at many phases of flight. To extend its use to the approach and landing phases, ground‐based augmentation system is an important on‐the‐ground technology to reduce the positioning errors. However, nonuniform spatial ionospheric delays need to be assessed during ground‐based augmentation system planning at each airport, particularly, in equatorial and low‐latitude regions. In this work, we analyze the statistics of ionospheric delay gradients around Suvarnabhumi airport, Thailand. The ionospheric delay gradients are estimated using single‐frequency code and carrier phase observation through the Kalman filter. To increase the success of the ratio test, the satellite elimination technique is then proposed. Based on the analysis between 2013 and 2016, we find that the background ionospheric delay gradients during equinox are higher than solstice, especially during September equinox 2013 when the gradients are about 9 mm/km. Moreover, the ionospheric delay gradients are more variable during daytime than nighttime.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Analysis of Quiet Time Vertical Ionospheric Delay Gradients Around Suvarnabhumi Airport, Thailand

2018

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“…In [13], [14], the single-frequency station-pair delay gradient estimation was proposed based on the L1 frequency with the Kalman filter and the LAMBDA method. The satellite elimination [15] was also applied to this method to increase the success of the estimation. [18] Datta-Barua et al [19] Lee et al [16] Lee et al [20] Single-frequency receiver Fujita et al [13] Budtho et al [21] Khanafseh et al [22] -Mixed-pair method Lee et al [20] However, for most areas in Thailand, the GNSS receivers are widely separated (more than 20 km baselines) since they are not originally intended for delay gradient monitoring.…”

Section: Introductionmentioning

confidence: 99%

Single-Frequency Time-Step Ionospheric Delay Gradient Estimation at Low-Latitude Stations

2020

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The irregularity of the local-area ionospheric delay is a primary impediment for Ground-Based Augmentation System (GBAS) services. Excessive ionospheric delay gradients may degrade aircraft positioning for high precision landing systems. Therefore, the spatial gradients of the nominal background ionosphere must be studied as their statistics will be sent to the approaching aircraft. For the well-known stationpair method, ionospheric delay gradient estimation requires at least 2 Global Navigation Satellite System (GNSS) reference stations. This method can be applied to both single or dual-frequency GNSS receivers. However, when the GNSS stations are far apart, it is not suitable for estimating the ionospheric delay gradients at short baselines, and the time-step method is an attractive alternative. In this work, we propose a singlefrequency time-step method for ionospheric delay gradient estimation. Careful baseline length selection is needed, due to ionospheric piercing point movements. We applied our method to GNSS data in 2014, at the peak of the 24th solar cycle, and showed that the standard deviations of the vertical ionospheric delay gradients were comparable to those derived from the dual-frequency time-step method. The standard deviations of vertical ionospheric gradients, VIG, ranged between 4 and 6 mm/km. The VIG values around the equinoxes were ~1.5 mm/km greater than at other times.

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Nominal ionospheric delay gradient estimation at Suvarnabhumi airport, Thailand

Cited by 2 publications

References 5 publications

Analysis of Quiet Time Vertical Ionospheric Delay Gradients Around Suvarnabhumi Airport, Thailand

Analysis of Quiet Time Vertical Ionospheric Delay Gradients Around Suvarnabhumi Airport, Thailand

Single-Frequency Time-Step Ionospheric Delay Gradient Estimation at Low-Latitude Stations

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