• Journal of Satellite, Information and Communications
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• v.12 no.2
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• pp.15-20
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• 2017

A conventional TV relay broadcast is a method of transmitting a program by means of a microwave, a leased wire, or a satellite. With the latest advances in LTE network, a relay approach using LTE mobile communications network has become increasingly competing with the traditional TV relay broadcast method. Since 2012, TV Chosun has been using the LTE network for marathon production, and channel A has also broadcast a marathon production broadcast using the LTE network. Therefore in this paper, we investigated the marathon relay method using LTE mobile communications network and compared with the traditional TV marathon relay method, and then suggested the optimum method for the marathon relay.

• Journal of Astronomy and Space Sciences
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• v.26 no.2
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• pp.199-210
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• 2009

Even though there are several Global Navigation Satellite Systems under development, only GPS and GLONASS are currently available for satellite positioning. In this study, GLONASS orbits were predicted from broadcast ephemeris using the 4th-order Runge-Kutta numerical integration. For accuracy validation, predicted orbits were compared with precise ephemeris. The RMS(Root Mean Square) and maximum 3-D errors were 14.3 km and 17.4 km for one-day predictions. In case of 7-day predictions, the RMS and maximum 3-D errors were 15.7 and 40.1 km, respectively. Also, the GLONASS satellite visibility predictions were compared with real observations, and they agree perfectly except for several epochs when the satellite signal was blocked by nearby buildings.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.193-202
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• 2016

The Korea Augmentation Satellite System (KASS), which is under development in Korea as a Satellite Based Augmentation System (SBAS) is expected to broadcast SBAS messages to air space in Korea according to the international standards defined by the International Civil Aviation Organization (ICAO) and the Radio Technical Commission for Aeronautics (RTCA). Around 13 SBAS messages are broadcast in every second to transmit augmentation information which can be applicable to a wide area in common. Each of the messages requires a different update interval and time-out according to the characteristics, purpose, and importance of transmitted information, and users should receive and combine multiple SBAS messages to calculate SBAS augmented information. Thus, a time to take acquiring first SBAS position by users differs depending on broadcasting various SBAS messages with which order and intervals. The present paper analyzes the considerations on message scheduling for broadcasting of KASS augmentation information and proposes a design of KASS message scheduler using the considerations. Compared to existing SBAS systems, which have a wide range of service area, a service area of the KASS is limited to Korea only. Thus, the numbers of ionosphere grid points and satellites to be augmented are expected to be smaller than those of existing SBAS. By reflecting this characteristic to the proposed design, shortening of broadcast interval of KASS message is verified compared to existing SBAS and a measure to increase a speed of acquisition of user navigation solution is proposed utilizing remaining message slots. The simulation result according to the proposed measure showed that the maximum broadcast interval can be reduced by up to 20% compared to that of existing SBAS, and users can acquire KASS position solution faster than existing SBAS.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.610-617
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• 2010

This paper analyzes the characteristics of abnormal broadcast GPS ephemeris by comparing distances between the receiver and the satellites. Effects of abnormal ephemeris on receiver's position estimate are closely related with range errors caused by variations of satellite positions. In more detail each range error depends on the satellite position error and the line of sight vector. Based on the fact, the ephemeris parameters are classified into three types depending on the size, the shape, and the shape of the satellite orbit to analyze the fault characteristics. The effects of satellite position errors caused by the three type s of parameters on the receiver's position estimate are analyze d in detail.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.347-356
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• 2020

In this study, Inclined Geosynchronous Orbit (IGSO) and Geostationary Orbit (GEO) of BeiDou System (BDS) and Quasi Zenith Satellite System (QZSS) satellites positions and clock errors calculated by broadcast ephemeris and compared with Multi-GNSS Experiment (MGEX) products provided by five Analysis Centers (ACs). Root Mean Square Errors (RMSE) calculated for satellite position error. The IGSO results showed that 1.82 m, 0.91 m, 1.28 m in BDS and 1.34 m 0.36 m 0.49 m in QZSS and the GEO results showed that 2.85 m, 6.34 m, 6.42 m in BDS and 0.47 m, 4.79 m, 5.82 m in QZSS in the direction of radial, along-track and cross-track respectively. RMS calculated for satellite clock error. The IGSO result showed that 2.08 ns and 1.24 ns and the GEO result showed that 1.28 ns and 1.12 ns in BDS and QZSS respectively.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.105-110
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• 2013

After analog broadcast changed to digital, the dynamic range of the broadcast audio became wider. As there are no regulation for digital broadcast audio level, the audio level of digital TV is gradually increasing, and this phenomenon is getting more serious. because of competition between broadcasters and programmes. To solve this problem, ITU-R legislated technical recommendations for digital TV audio level. In this paper, the audio levels of domestic TV channels are measured according to the algorithm of the ITU-R, and analyzed management method is suggested.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.95-101
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• 2015

The backup site operation of the Image Data Acquisition and Control System (IDACS) for Communication Ocean Meteorological Satellite (COMS) is discussed in terms of the ground station configuration, image data processing, and the characteristics of backup activities for both the meteorological image data and the ocean image data. The well-performed backup operation of the COMS IDACS is also confirmed with the first three years normal operation results from April, 2011 to March, 2014. The operation results are analyzed through statistical approach to provide the achieved operational performance of the image data reception, preprocessing, and broadcast.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.201-208
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• 2019

Numerical integration is necessary for satellite orbit determination and its prediction. The numerical integration algorithm can be divided into single-step and multi-step method. There are lots of single-step and multi-step methods. However, the Runge-Kutta method in single-step and the Adams method in multi-step are generally used in global navigation satellite system (GNSS) satellite orbit. In this study, 4th and 8th order Runge-Kutta methods and various order of Adams-Bashforth-Moulton methods were used for GLObal NAvigation Satellite System (GLONASS) orbit integration using its broadcast ephemeris and these methods were compared with international GNSS service (IGS) final products for 7days. As a result, the RMSE of Runge-Kutta methods were 3.13m and 4th and 8th order Runge-Kutta results were very close and also 3rd to 9th order Adams-Bashforth-Moulton results. About result of computation time, this study showed that 4th order Runge-Kutta was the fastest. However, in case of 8th order Runge-Kutta, it was faster than 14th order Adams-Bashforth-Moulton but slower than 13th order Adams-Bashforth-Moulton in this study.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.953-961
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• 2011

IGS (International GNSS Service) predicted orbits contained in IGS ultra-rapid orbits is suitable for real-time or near-real-time precise positioning. In this paper, we analyzed orbit anomalies of the IGS predicted orbits and detected the anomalies NANU (Current Notice Advisories to NAVSTAR Users) messages and IGS BRDC (Broadcast Ephemerides). As a results, the orbit anomalies of the predicted orbits were observed 93 times in 2010. In case of using the NANUs, we could get detection performance of 88% about the IGS predicted orbits's anomalies. And we could achieve 95% detection performance when the NANUs and BRDCs were used together.

• Journal of Satellite, Information and Communications
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• v.10 no.3
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• pp.57-61
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• 2015

This paper describes the basic principles of 3D broadcast system and proposes new 3D broadcast technology that reduces the amount of data by applying CS(Compressed Sensing). Differences between Sampling theory and the CS technology concept was described. CS algorithm SS-CoSaMP(Single-Space Compressive Sampling Matched Pursuit) and AMP(Approximate Message Passing) was described. Image data compressed and restored by these algorithm was compared. Calculation time of the algorithm having a low complexity is determined.