• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.481-488
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• 2021

The satellite telecommand processing system is the only way to provide telecommands for status monitoring, control, and mission execution. Domestic satellites can be divided into science, technology, and multi-purpose satellites, and geostationary satellites. These Satellites uses CCSDS standard protocol to communicate with ground stations. However, existing domestic satellites use only software to decode telecommands which increases cost of software development and verification of the developed software. Performance of software only approach is relatively low compared to hardware. In this paper, we present ASIC processing system specifically designed to decode telecommands. The system consists of a telecommand RAM, a protocol RAM/ROM, an ASIC, an interface unit of FPGA, and a relay block. The system handles general commands and pulse commands that are used in satellites. We established a ground station equipment and test environment to verify the system functionality, The result shows that our system reduces the development cost by 1/5 and improves the performance by 10⁵ times compared to the previous systems that decode telecommands only by software.

• Journal of Astronomy and Space Sciences
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• v.28 no.4
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• pp.319-332
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• 2011

The objectives of this study are to analyze the satellite visibility at the randomly established ground sites, to determine the five optimal ground sites to perform the optical surveillance and tracking of domestic satellites, and to verify the acquisition of the optical observation time sufficient to maintain the precise ephemeris at optimal ground sites that have been already determined. In order to accomplish these objectives, we analyzed the visibility for sun-synchronous orbit satellites, low earth orbit satellites, middle earth orbit satellites and domestic satellites as well as the continuous visibility along with the fictitious satellite ground track, and calculate the effective visibility. For the analysis, we carried out a series of repetitive process using the satellite tool kit simulation software developed by Analytical Graphics Incorporated. The lighting states of the penumbra and direct sun were set as the key constraints of the optical observation. The minimum of the observation satellite elevation angle was set to be 20 degree, whereas the maximum of the sun elevation angle was set to be -10 degree which is within the range of the nautical twilight. To select the candidates for the optimal optical observation, the entire globe was divided into 84 sectors in a constant interval, the visibility characteristics of the individual sectors were analyzed, and 17 ground sites were arbitrarily selected and analyzed further. Finally, five optimal ground sites (Khurel Togoot Observatory, Assy-Turgen Observatory, Tubitak National Observatory, Bisdee Tier Optical Astronomy Observatory, and South Africa Astronomical Observatory) were determined. The total observation period was decided as one year. To examine the seasonal variation, the simulation was performed for the period of three days or less with respect to spring, summer, fall and winter. In conclusion, we decided the optimal ground sites to perform the optical surveillance and tracking of domestic satellites and verified that optical observation time sufficient to maintain the precise ephemeris could be acquired at the determined observatories.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.9
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• pp.791-800
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• 2021

In this paper, the recent development trends of civil/military earth observation satellites of space-advanced countries and South Korea are investigated and the current status and the direction of prospective domestic satellite projects is described. The space-advanced countries are the United States, Russia, France, Germany, Italy, Israel, China and Japan. Based on the recent trends, the direction of prospective earth observation satellites is predicted. In general, the term of 'satellite development' usually refers to a concept of satellites, ground stations and launch vehicles consisting a satellite system, but in this paper the term focuses on the development of satellites, not the satellite system.

• Journal of Astronomy and Space Sciences
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• v.32 no.4
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• pp.349-355
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• 2015

As a governmentally approved domestic entity for Space Situational Awareness, Korea Astronomy and Space Science Institute (KASI) is developing and operating an optical telescopes system, Optical Wide-field PatroL (OWL) Network. During the test phase of this system, it is necessary to determine the range of brightness of the observable satellites. We have defined standard magnitude for Low Earth Orbit (LEO) satellites to calibrate their luminosity in terms of standard parameters such as distance, phase angle, and angular rate. In this work, we report the optical brightness range of five LEO Satellites using OWL-Net.

• The Korean Journal of Air & Space Law and Policy
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• v.32 no.1
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• pp.385-417
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• 2017

Insurances of space activities are divided into satellite insurance, astronaut insurance and third party liability insurance. Against the background of the rapid development of space commercialization, especially the increasing participation of private entities in space affairs, the present international and domestic mechanisms of space insurance are challenged. As a space-faring state which is in the process of developing space businesses, the regulations of space insurance in China are deserved to be discussed. Satellites insurance is at present well-developed, the "pre-launch", "launch" and "in-orbit" phases of satellites are all possible to be insured by related companies. China created the CAIA in 1997 to provide insurance for Chinese satellites. However, with more private entities start to involve in space as well as satellite industry, the regime established under the framework of CAIA is necessary to be modified, and the mechanism relating to space insurance brokers should be promoted. The astronauts are recognized as the envoy of humankind, and relevant international regulations are made to provide assistance to them in emergency circumstances. From the domestic perspective, astronauts will be fully insured. China creates a particular type of insurance for astronauts. However, once space tourism becomes a business, the insurance of the tourist will be demanded to be created. In order to promote China's space tourism, it is recommended to take the "Astronaut Group Insurance" as an optional model to space tourists, if the tourists are customers of a governmental-owned space company. Once private involvement of providing orbital/suborbital tourism service becomes a reality, new rules are required. Getting a third party liability insurance is deemed as an indispensable precondition for an applicant to get a launch permission. Domestic space laws will include provisions for the third party liability insurance. China's "Interim Measures" of 2002 realizes the importance of third party liability insurance and requires the permit holder to get it before entering the launching site. This regulation is different from the practices of other states. Concerning that China is the sponsor of APSCO, for the purpose of promoting commercial space cooperation, a harmonized approach to domestic law is recommended to be found.

• Electronics and Telecommunications Trends
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• v.38 no.1
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• pp.55-64
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• 2023

Recently, preparations for 6G have led to the increasing interest in integrated or hybrid communication networks considering low-orbit satellite communication networks with terrestrial mobile communication networks. In addition, the demand for frequency allocation for new mobile services from low-orbit small satellites to provide global internet of things (IoT) services is increasing. The operation of such satellites and terrestrial mobile communication networks may inevitably cause interference in adjacent bands and the same band frequency between satellites and terrestrial systems. Focusing on the results of the recent ITU-R WP4C meeting, this study introduces the current status of frequency sharing and interference issues between satellites and terrestrial systems, and frequency allocation issues for new mobile satellite operations. Coexistence and compatibility studies with terrestrial IMT in L band and 2.6 GHz band, operated by Inmassat and India, respectively, and a new frequency allocation study (WRC-23 AI 1.18) are carried out to reflect satellite IoT demand. For the L band, technical requirements have been developed for emission from IMT devices at 1,492 MHz to 1,518 MHz to bands above 1,518 MHz. Related studies in the 2 GHz and 2.6 GHz bands are not discussed due to lack of contributions at the recent meeting. In particular, concerning the WRC-23 agenda 1.18 study on the new frequency allocation method of narrowband mobile satellite work in the Region 1 candidate band 2,010 MHz to 2,025 MHz, Region 2 candidate bands 1,695 MHz to 1,710 MHz, 3,300 MHz to 3,315 MHz, and 3,385 MHz to 3,400 MHz, ITU-R results show no new frequency allocation to narrow mobile satellite services. Given the expected various collaborations between satellites and the terrestrial component are in the future, interference issues between terrestrial IMT and mobile satellite services are similarly expected to continuously increase. Therefore, participation in related studies at ITU-R WP4C and active response to protect terrestrial IMT are necessary to protect domestic radio resources and secure additional frequencies reflecting satellite service use plans.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.8
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• pp.702-709
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• 2016

By means of the our satellite development for the past 20 years, it ensure us to obtain domestic independent development capabilities. In the case of practical-class Low-Earth Orbit(LEO) remote sensing satellites, we become a world-class developer. Furthermore, we acquire the technology to develop domestic-leading geostationary satellites, depending on the mission. Currently, we proceed with the next-generation mid-size satellite development program featuring standard bus for the expansion of the world market and has embarked on the development of lunar orbiter from this year.

• Journal of Astronomy and Space Sciences
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• v.34 no.1
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• pp.19-30
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• 2017

The optical wide-field patrol network (OWL-Net) is a Korean optical surveillance system that tracks and monitors domestic satellites. In this study, a batch least squares algorithm was developed for optical measurements and verified by Monte Carlo simulation and covariance analysis. Potential error sources of OWL-Net, such as noise, bias, and clock errors, were analyzed. There is a linear relation between the estimation accuracy and the noise level, and the accuracy significantly depends on the declination bias. In addition, the time-tagging error significantly degrades the observation accuracy, while the time-synchronization offset corresponds to the orbital motion. The Cartesian state vector and measurement bias were determined using the OWL-Net tracking data of the KOMPSAT-1 and Cryosat-2 satellites. The comparison with known orbital information based on two-line elements (TLE) and the consolidated prediction format (CPF) shows that the orbit determination accuracy is similar to that of TLE. Furthermore, the precision and accuracy of OWL-Net observation data were determined to be tens of arcsec and sub-degree level, respectively.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.13 no.4
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• pp.100-110
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• 2005

The worldwide satellite system for search and rescue has been in operation since 1982 and has assisted in the rescue of thousands of lives in distress. Aviators, mariners and land users being equipped with distress beacons are capable of transmitting distress signals to the satellites in emergency situations anywhere in the world. This paper describes the configuration of the search and rescue satellite system, principles of its operation, and how the system is utilized to process the distress events. Also, this paper points out the importance of development of technologies of user equipment and proposes an experimental program for technology development using domestic satellites.

• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.63-72
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• 2003

On the basis of sensor types, satellites can be classified by two types, which are optical observation satellite and radar observation satellite. A satellite type is selected according to the specific mission. Optical observation satellite is more appropriate for getting high geometric resolution images and radar observation satellite is more appropriate for getting images independent of weather condition the more a demand of satellite increases, the more an importance of information increases. Therefore, development trend and state of earth observation satellite are surveyed and described in this paper. In the future, domestic development of satellites will be planned considering trend of satellite technologies.