• Journal of the Korea Society of Computer and Information
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• v.22 no.9
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• pp.57-64
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• 2017

CCSDS Standard is widely used in the international space telecommunication area. But standard recommendation of CCSDS is not restrictive, so, we can select an appropriate encryption protocol among the layer. For synchronization, encryption sync is attached in the beginning of the encrypted data. In the exceptional environmental condition, although the receiver can not decrypt the normal data, the sender have no conception of that situation. In this paper, we propose a two-stage SES alarmed link encryption synchronization method having optimized threshold value necessary to decide whether the receiver has a correct decryption or not. first, through the experiment of mutual relations between error rate and encryption synchronization detection error, we can predict worst communication environment for the selected encryption synchronization pattern. second, through the experiment for finding what number of consecutive frame synchronization error is an appropriate reference value and analysis of that experiment, we suggest an optimized threshold value for resynchronization request. lastly, through the output images we can predict the probability error that should be guaranteed by channel coder.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.91-98
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• 2013

Computing environment of space explorer including LEO (Low Earth Orbit), GEO (Geosynchronous Earth Orbit) satellite may be considered as the same category of embedded system on the ground. But with comparison with personal computing environment it is widely accepted that the space computing is outdated and behind of state of the art. Especially file system which is nearly essential item in all ground computing environment including personal computer, workstation and server is rarely used in space explorer till lately. In this paper, a study of ESA PUS (Packet Utilization Standard) and CCSDS (Consultative Committee for Space Data Systems) community's activity, international trend, and applicable technical application for applying file system in oder to use these standards for utilizing the file system to deep space explorer is described.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.157-163
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• 2007

The purpose of this study is to design and simulate Reed Solomon encoder(255,223) in PCM/FM communication system in order to transmit the KSLV-I onboard video data. Especially in the compressed video data transmission applications, the communication system is required to have a very low BER performance because of interframe or interframe compression techniques. We have used the primitive polynomial of CCSDS standard and calculated the various coefficients and then the encoder have been simulated as a part of RF interface FPGA hardware in a video compression unit.

• Bulletin of the Korean Space Science Society
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• 2005.10a
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• pp.79-79
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• 2005

• Bulletin of the Korean Space Science Society
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• 2007.10a
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• pp.106-106
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• 2007

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.12
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• pp.2891-2898
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• 2013

CCSDS Standard is widely used in international space telecommunication area. In this standard, Encryption is realized using a unique hierarchical encryption protocol and satisfied security requirements of communication channels. For synchronization, encryption sync is attached in the beginning of encrypted data. But exceptional case(timing jittering, abnormal system shutdown, etc.) is occurred, receiving equipment cannot decrypt received data. In this paper, we propose a SES Alarmed link encryption synchronization method for sending warning signal to the transmitter when some problems have been occurred during the transmission and we also suggest optimum conditions for SES Alarm signal through performance analysis.

• 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.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.810-814
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• 2002

According to the image level definition for KOMPSAT-2 in KOMPSAT-2 Ground Station Specification, the level 0 is frame formatted, unprocessed data at full resolution; any and all communications artifacts (e.g., synchronization frames, communications headers) removed. The level 0 is used for two purposes: 1) exchange of imagery between image receiving & processing element (IRPE), and 2) image transfer from the Receiving & Archiving Subsystem to Search & Processing Subsystem. On-board processing of imagery data of KOMPSAT-2 includes JPEG-like compression and encryption besides conventional CCSDS packetization. The encryption is used to secure imagery data from any intervention during downlink and compression allows real-time downlink of image data reducing data rate produced from the camera. While developing ground receiving system for KOMPSAT-2, it was necessarily to define level 0 products. In this paper, we will suggest level 0 product definition for KOMPSAT-2 and explain reasons of the decisions made. The key factor used while defining the level 0 products is the efficiency of whole ground receiving system. The latter half of the paper will explain the implementation of software that generates level 0 products. The necessary steps to produce level 0 products will be explained, and the performance achieved will be presented.

• Bulletin of the Korean Space Science Society
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• 2004.04a
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• pp.73-73
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• 2004

KOMPSAT-2 위성에서 사용되는 원격명령어와 텔레메트리는 국제표준규격인 CCSDS format을 따르고 있다. 이들 원격명령어와 텔레메트리는 KOMPSAT-1의 heritage에 따라 구성되었으나 테스트 단계를 거치는 동안 여러 가지 형식의 원격명령어와 텔레메트리가 추가되었으며 각 유닛의 프로세서와 탑재컴퓨터간의 충돌을 피하기 위해 그 구현 및 전달 방식도 보다 복잡해졌다. 본 논문에서는 KOMPSAT-2에서 사용되고 있는 원격명령어와 텔레메트리의 각 타입을 분석하고 유닛 별로 구현 및 전달 방식이 어떻게 달라지는 지 보여준다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.230-232
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• 1999

KOMPSAT(KOrea Multi-Purpose SATEllite) Flight Software[2]의 개발 단계에서 통합 및 시험, 검증 시험을 위해 실제 시스템과 유사한 환경을 제공하는 개발도구로서 STB(Software Test BED)를 개발하였으며 STB 구성중에서 Command/Telemetry (CMD/TLM) 테스트를 위해 개발한 Command Generator / Telemetry Analyzer에 관한 내용을 본 논문에서 설명하고자 한다. 통신간에 사용되는 프로토콜은 [1]에서 언급한 바와 같이 CCSDS 프로토콜을 따르고 모든 관련된 Command 와 Telemetry 형식 또한 [1]에서 언급한 바와 같다. 이 구현된 소프트웨어를 이용하여 Flight Soaftware내의 CMD/TLM 처리 소프트웨어의 기능시험과 검증시험을 수행하였다.