• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.262-271
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• 2024

In this paper, by applying deep learning, one of the A.I. techniques, through angle information, which is optical observation data generated when observing satellites at observatories, distance information from observatories is learned to predict range data, thereby increasing the precision of satellite's orbit determination. To this end, we generated observational data from GMAT, reduced the learning data error of deep learning through preprocessing of the generated observational data, and conducted deep learning through MATLAB. Based on the predicted distance information from learning, trajectory determination was performed using an extended Kalman filter, one of the filtering techniques for trajectory determination, through GMAT. The reliability of the model was verified by comparing and analyzing the orbital determination with angular information without distance information and the orbital determination result with predicted distance information from the model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.685-688
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• 2016

SBAS(Satellite Based Augmentation System) broadcasts the correction message based on satellite communication to improve the positioning accuracy of GNSS user. For this reason, SBAS is actively being utilized on navigation part. To apply SBAS to navigation part, it should satisfy not only accuracy but also integrity, continuity, availability, coverage requirements and so on. Since SBAS reference station is the base infrastructure of SBAS, it is the main factor to determine the environment, position, and geometry of reference stations to achieve SBAS service performance. Therefore, a site environmental analysis should be performed prior to the selection of SBAS reference station. In this paper, it performs the environmental analysis of NDGPS(Nationwide Differential GPS) reference station sites on the premise that SBAS reference station will be co-operated in the same site of NDGPS operated by MOF(Ministry of Oceans and Fisheries). The environmental analysis is conducted as carrying out the visibility analysis of GPS satellite and interference analysis. This paper also presents the brief procedures and requirements for site survey of SBAS reference station.

• Journal of Advanced Navigation Technology
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• v.4 no.2
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• pp.152-161
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• 2000

Recently, it is considered to combine the GPS receiver with the GLONASS for the improvement of performance and accuracy. This combined system reduces errors by SA for GPS, and has merits to select receivable satellite. In this paper, aperture-coupled patch antenna and small sized ceramic dielectric patch antenna are designed and implemented for GPS/GLONASS combined receiver, which show a wideband characteristics with circular polarization. The manufactured antennas have the bandwidth more than 240 MHz, VSWR less than 1.5:1, and the axial ratio less than 3dB, and satisfy required characteristics of the GPS/GLONASS antenna.

• Journal of Satellite, Information and Communications
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• v.11 no.1
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• pp.1-5
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• 2016

In this paper, High Power Pulsed Amplifier with wide-band characteristic is implemented for L-band Navigational Aid(NAVAID). Due to the characteristics of L-Band NAVAID, implemented SSPA is demanded characteristics of high RF power, high linearity and high efficiency. Therefore, in this paper, efficiency characteristic is improved by modified class F technique. And linearity characteristic is improved by balance structure using hybrid coupler, $2^{nd}$ & $3^{rd}$ harmonic trap and anti-phase technique using non-linear characteristics of drive amplifier. Implemented SSPA shows that bandwidth of 300MHz, RF Output power of 1.5KW and efficiency of 55%.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.593-601
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• 2012

This paper develops and analyzes a new multiple-hypothesis Receiver Autonomous Integrity Monitoring (RAIM) algorithm as a candidate for future standard architecture. The proposed algorithm can handle simultaneous multiple failures as well as a single failure. It uses measurement residuals and satellite observation matrices of several consecutive epochs for Failure Detection and Exclusion (FDE). The proposed algorithm redueces the Minimum Detectable Bias (MDB) via the Relative RAIM (RRAIM) scheme. Simulation results show that the proposed algorithm can detect and filter out multiple failures in tens of meters.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.517-522
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• 2011

Global Navagation Satellite System(GNSS) is divided into Local Area Differential GNSS and Wide Area Differential GNSS. Wide Area DGNSS has more complicated structure and massage type. And transfer rate is limited, so efficient message scheduling algorithm is needed to guarantee user's accuracy and integrity. There are about 30 message types in Wide Area DGNSS. Each message type has different update interval. In this paper, the performances of message scheduling algorithm for Wide Area Differential GNSS are investigated. For all message types, results show that max update time interval requirement is satisfied.

• Journal of Advanced Navigation Technology
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• v.22 no.5
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• pp.409-414
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• 2018

Extrapolating the correction information of ionosphere is essential for expanding wide area differential GPS (WADGPS) service area beyond the reference station network. In this paper, design and analysis of the artificial neural network for expanding the ionospheric correction region will be proposed. First, analysis about influence of each input of neural network were performed. The inputs are the day/year periodic function, sunspot number, and geomagnetic index (Ap). Second, performance analysis with respect to the number of hidden layers and neurons in the neural network is shown. As a result, estimation of total electron contents (TEC) on the high/low latitude regions in solar max(2014) are displayed.

• Journal of Advanced Navigation Technology
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• v.17 no.3
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• pp.271-278
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• 2013

In this paper, ECEF to ECI coordinate transformation algorithm which uses EOP parameters in GPS civil navigation message is introduced, and ECEF to ECI coordinate transformation simulation results were analyzed. The ECEF to ECI coordinate transformation includes GPS to UTC, and UTC to other types of time conversions and EOP data processing algorithms. The ECEF to ECI coordinate conversion algorithm was certified using real LEO satellite position, velocity GPS data, and EOP data which offered by the Earth Orientation Center.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.740-745
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• 2023

This study proposes the development of an antenna tracker system using a satellite system to stabilize the communication status of drones and extend the communication distance. The location information of the drone and the ground station was used to maximize communication gain in the general fixed antenna method between the ground station and the drone. We developed a tracker system that can automatically and continuously aim the ground station's antenna at the drone. It is expected that the use of antenna trackers will improve the stabilization of communication conditions and expand the communication distance, thereby leading to the advancement of the drone industry.

• Journal of Advanced Navigation Technology
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• v.22 no.6
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• pp.610-615
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• 2018

Globally, global navigation satellite system (GNSS) is being developed and operated in advanced countries. China's Beidou is developing rapidly, starting with global positioning system (GPS), which is the most representative system. In this paper, we analyze the visibility of Beidou satellite in Korea at present time to utilize rapidly changing Beidou. In this analysis, it is compared with GPS which is stable service. The results of the visibility analysis are based on the results of the mask angle (the low elevation satellite exclusion angle) and the result of the skyplot (a visual representation of the position of the satellite at the user location). Visibility analysis shows that the high elevation angle of Beidou satellite is higher than that of GPS satellite in Korea. In addition, GPS and Beidou's availability and positioning accuracy analysis are performed to confirm the effect of increasing elevation angle satellites. According to the results, Beidou is more effective than GPS in using high elevation satellites in Korea.