• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.69-75
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• 2011

As part of its space development program, Korea has a plan for the launch of a lunar orbiter and a lunar lander. To enable the transmission of lunar information based on multimedia, it is necessary to construct a communication system that is capable of transmitting large-volume telemetry data. The CCSDS standard recommends the deferred NAK mode as ARQ scheme for reliable long-distance deep-space communication systems. In this paper, we implement a space communication system simulator in the deferred NAK mode using models of the lunar orbiter, the earth station, and the space environment. The simulator employs modulation techniques and turbo coding schemes for transmitting large-volume telemetry data. We analyze the transmission performance of telemetry data through the simulation.

• Journal of Satellite, Information and Communications
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• v.1 no.2
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• pp.25-31
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• 2006

The COMS (Communication, Ocean, and Meteorological Satellite) performing meteorological and ocean monitoring and providing communication service with meteorological, ocean and Ka-band payload in the geostationary orbit includes MODCS (Meteorological and Ocean Data Communication Subsystem) which provides transmitting the raw data collected by meteorological payload called MI (Meteorological Imager) and ocean payload named GOCI (Geostationary Ocean Color Imager) to the ground station and relaying the meteorological data processed on the ground to the end-user stations. MODCS comprises of two channels: SD channel which formats the raw data according to CCSDS recommendation, amplifies and transmits its signal to the ground station; MPDR channel which relays to the end-user stations the ground-processed meteorological data in the data format of LRIT/HRIT recommended by CGMS. This paper constructs the architecture of MODCS for transmitting and relating the observed data, and investigates that the key performance parameters have the required margin through the preliminary performance analyses.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.134-141
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• 2020

Telemetry system is a communication system that measures and transmits various signals in the aircraft to the ground for collecting and monitoring flight data during the development of unmanned air vehicle and satellite launch vehicles. With the recent development of wireless communication technology, it is becoming important to apply encryption of telemetry system to prepare with security threats that may occur during flight data transmission. In this paper, we suggested and implemented the application method of ARIA-256, Korean standard encryption algorithm, to apply encryption to telemetry system. In consideration of the block error propagation and the telemetry frame characteristics, frame is encrypted using the CTR mode and can apply the Reed-solomon codes recommended by CCSDS. ARIA algorithm and cipher frame are implemented in FPGA, and simulation and hardware verification system confirmed continuous frames encryption.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.98-105
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• 2005

In this paper, the decryption function of CCSDS telecommand of CTU EQM for the security of communications satellite was verified. In order to intensify the security level of DES CFB decryption algorithm applied to CTU EM, 3DES CFB decryption algorithm using three keys is implemented in the CTU EQM. As the decryption keys increased due to the 3DES algorithm, the keys and IV are stored in PROM memory, and used for the telecommand decryption by taking the keys and IVs corresponding to the selected key and IV indexes from the memory. The operation of the 3DES CFB is validated through the timing simulation of 3DES CFB algorithm, and then the 3DES CFB core implemented on the A54SX32 FPGA. The test environment for the telecommand decryption verification of the CTU EQM was built up. Through sending and decrypting the encrypted command, monitoring the opcodes, and confirming LED on/off by executing the opcodes, the 3DES CFB telecommand decryption function of the CTU EQM is verified.

• The Korean Journal of Archival Studies
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• no.16
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• pp.39-96
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• 2007

Traditionally, the concept of transfer is that physical records such as paper documents, videos, photos are made a delivery to Archives or Records centers on the basis of transfer guidelines. But, with the automation of records management environment and spreading new records creation and management applications, we can create records and manage them in the cyberspace. In these reasons, the existing transfer system is that we move filed records to Archives or Records centers by paper boxes, needs to be changed. Under the needing conditions of a new transfer paradigm, the fact that the revision of Records Act that include some provisions about electronic records management and transfer, is desirable and proper. Nevertheless, the electronic transfer provisions are too conceptional to apply records management practice, so we have to develop detailed methods and processes. In this context, this paper suggest that a electronic records transfer process model on the basis of international standard and foreign countries' cases. Doing transfer records is one of the records management courses to use valuable records in the future. So, both producer and archive have to transfer records itself and context information to long-term preservation repository according to the transfer guidelines. In the long run, transfer comes to be the conclusion that records are moved to archive by a formal transfer process with taking a proper records protection steps. To accomplish these purposes, I analyzed the 'OAIS Reference Model' and 'Producer-Archive Interface Methodology Abstract Standard-CCSDS Blue Book' which is made by CCSDS(Consultative committee for Space Data Systems). but from both the words of 'Reference Model' and 'Standard', we can understand that these standard are not suitable for applying business practice directly. To solve this problem, I also analyzed foreign countries' transfer cases. Through the analysis of theory and case, I suggest that an Electronic Records Transfer Process Model which is consist of five sub-process that are 'Ingest prepare ${\rightarrow}$ Ingest ${\rightarrow}$ Validation ${\rightarrow}$ Preservation ${\rightarrow}$ Archival storage' and each sub-process also have some transfer elements. Especially, to confirm the new process model's feasibility, after classifying two types - one is from Public Records center to Public Archive, the other is from Civil Records center to Public or Civil Archive - of Korean Transfer, I made the new Transfer Model applied to the two types of transfer cases.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.7
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• pp.39-47
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• 1997

The mission of the TTC system is to acquire and process the telemetry data from the satellite and to provide mission planning and satellite control for the target stellite system. In this paper, the transmission scheme for the Tracking, Telemetry and Command(TTC) system of satelliteis described and determined according to the recommendation of CCSDS, and the channel characteristics are analyzed according to modulation method. Expecially, we introduced the concepts of carrier vs. telemetry data power ratio which causes the channel performance to degrade, and analyzed the effects of transmission performance according to the power ratio of carrier vs. telemetry data and the modulation index. The channel of the LEO TTC sytem is different with usual satellite communication system. So, we have generalized the link budget of TTC sytem for using the link budget of ground station well-known and proposed the determination method of modultion indices for improveing channel performance.

• Journal of Astronomy and Space Sciences
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• v.27 no.1
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• pp.11-20
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• 2010

This paper designs a data link between a Lunar Orbiter (LO) and an Earth Station (ES), and analyzes the downlink performance of a space communications system for lunar exploration, conforming to the recommendations by the Consultative Committee for Space Data Systems (CCSDS). The results provided in the paper can be useful references for the design of reliable communication link for the Korean lunar exploration in the near future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.1
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• pp.42-49
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• 2011

Telemetry link requires high data rate to transmit the multimedia data for lunar explorations in space communications. In this paper, we analyze a data rate with the modulation and channel coding schemes based on Consultative Committee for Space Data Systems (CCSDS) in S, X, Ku and Ka bands, respectively. Then, we suggests modulation and channel coding schemes to meet the link margins and have a maximum data rate for lunar explorations in telemetry links.

• Bulletin of the Korean Space Science Society
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• 2003.10a
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• pp.64-64
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• 2003

위성탑재용 정보 보호 토큰 처리기는 위성 운용시 관제권에 대한 제어 및 관제 데이터의 보안을 위한 코드 처리기로 위성의 명령 및 제어기의 앞단에 두어 위성의 관제를 위한 제어 코드를 관리하도록 함으로 유사시 위성 통신망의 운용을 독점하여 악의의 사용자가 위성의 관제권을 획득하지 못하도록 하기 위한 정보 보호용 토큰 처리 시스템이다. 본 정보 보호 토큰 처리기는 평상시에는 다수의 허가된 사용자가 위성망에 접근할 수 있도록 CCSDS등 표준화된 코드체계를 사용하지만, 필요 시에는 표준코드 이외에 보안 처리된 코드를 사용함으로 통신망을 보호하고 관제권을 독점할 수 있다. 정보 보호 토큰 처리기와 같은 위성 탑재용 시스템은 위성이 운용되는 우주 공간에서 보다 안정적으로 운용될 수 있도록 고 신뢰의 시스템 설계 기술이 필요하며, 본 논문에서는 우주 공간의 동작 환경 중 우주 방사선에 의한 전자회로의 동작 오류를 검출하고 정정하는 기법에 대하여 분석하고 위성에 탑재 가능한 시스템 구성을 위한 정보 보호 토큰 처리기를 설계하였다. 또한 위성의 운용 중 시스템의 보안 체계를 바꿀 수 있도록 설계하여 정보보호 토큰의 코드 노출에 대처하도록 하였다.

• Journal of Astronomy and Space Sciences
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• v.27 no.2
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• pp.129-134
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• 2010

Rain attenuation can cause a serious problem that an availability of space communication link on Ka band becomes low. To reduce the effect of rain attenuation on the error performance of space communications in Ka band, an adaptive coding and modulation (ACM) scheme is required. In this paper, to achieve a reliable telemetry data transmission, we propose an adaptive coding and modulation level using turbo code recommended by the consultative committee for space data systems (CCSDS) and various modulation methods (QPSK, 8PSK, 4+12 APSK, and 4+12+16 APSK) adopted in the digital video broadcasting-satellite2 (DVB-S2).