• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.8
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• pp.1485-1492
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• 1994

In this paper, we design and implement the Combline Bandpass Filters for the satellite transponder by using the least-squares curve-fitting method. The Combline Bandpass Filters are located front of the mixer and behind of it, which is the component of down converter. Comparing with the filters which have $\lambda$/4 resonance length. Combline Filter has wide range of stop-band by using $\lambda$/8. So, it is useful to the satellite transponder owing to its low mass and small size. The filters described are realized as coupled rectangular coaxial transmission lines. The choice of this type is due to the ease of machining and wide variations in coupling coefficients rather than the use of the round rod resonators. We determine 800 MHz bandwidths for the combline bandpass filters. By using Chebyshev filter function, we design and implement 4-pole combline filters.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1728-1735
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• 2011

In this paper, satellite data link waveform is proposed which is based on the waveform of Link-16 but LDPC code is studied instead of CCSK code in order to be optimized to satellite nonlinear channel environment and transmission characteristics. And the DSM (Demux, Selective CH switch, and Mux) transponder structure is suggested which can remove all of the jamming signal out of the transmission signal band and convert uplink hopping frequency to desired ones of downlink. The results of BER and anti-jamming performance analysis shows that the required Eb/No and processing gain in the worst case partial band jammer of the proposed waveform are 2.5dB and 52dB respectively and the anti-jamming capacity improvement of DSM transponder is maximum 2dB.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.1
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• pp.64-72
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• 1986

The error rate equation fo DS-BPSK(Direct Sequence Binary Phase Shift Keying) signal transmitted through the nonlinear satellite transponder has been derived in the cochannel interference and downlink Gaussian noise environment. The input to the satellite transponder is the superposition of DS-BPSK signal with one interfere which is a cochannel wide-band PN signal. The error rate performance of DS-BPSK system has been evaluated and shown in figures in terms of carrier to interference power ratio(CIR), downlink signal to noise power ratio(downlink SNR) and process gain. In the analysis, it has been shown that the use of a hard limiter in DS-BPSK satellite system leads to the generation of narrow-band intermodulation products which is independent of the process gain. Also it is known that the error rate performance can be improved in the low levels (below 10dB) of CIR as the CIR increase. As the process gain varies from 10 to 100 the curve gives the about 10 dB gain in downlink SNR to maintain a fixed error rate.

• ETRI Journal
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• v.30 no.2
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• pp.261-267
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• 2008

In this paper, we propose and demonstrate a cost-effective technique to upgrade the capacity of dense wavelength division multiplexing (DWDM) networks to a 40 Gb/s line rate using the existing 10 Gb/s-based infrastructure. To accommodate 40 Gb/s over the link optimized for 10 Gb/s, we propose applying a combination of super-FEC, carrier-suppressed return-to-zero, and pre-emphasis to the 40 Gb/s transponder. The transmission of 40 Gb/s DWDM channels over existing 10 Gb/s line-rate long-haul DWDM links, including $40{\times}40$ Gb/s transmission over KT's standard single-mode fiber optimized for 10 Gb/s achieves successful results. The proposed upgrading technique allows the Q-value margin for a 40 Gb/s line rate to be compatible with that of 10 Gb/s.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7A
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• pp.557-562
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• 2003

An output multiplexer of manifold type is widely used in a recent satellite transponder for its mass and volume reduction. For correct operation, the filters of such a multiplexer must be singly terminated. In this paper, a simple synthesis method of a 6-pole dual-mode singly-terminated filter is described. From the transfer function of the filter, network parameters such as in/output terminations and coupling coefficients are obtained easily without complicated matrix algebra such as orthogonal projection and similarity transformation. Two different-structure filters are taken into consideration and the network parameters of each filter have been extracted from the same transfer function. It is shown that the responses of two filters are same to each other since their network parameters are obtained from the same transfer function. The method described in this paper can be applied to the other degree singly terminated filter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.11
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• pp.1084-1094
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• 1991

Upon introducing satellite communication system to korea, one of the important problems to copy with is the effect from the probable intentional interference i. e. jamming. In this paper, we have considered the M any PSK signal and the soft limiter type, which contains hard limiter, nonhnear satellite transponder in environments of uplink tone or noise jamming plus Gaussian noise and downlink Gaussian noise. Using the derived error rate equation, we have evaluated numerically the error performance of BPSK and QPSK system, and shown in figures in terms of upink and downink earner to jamming rater(CJR) and limiting level. From the results we have known that tone jamming effect on the error performance in BPSK and QPSK signals in nonlinear satelhie shnnel become less with increasing the uplink CNR and with decreasing the liniting level. And in a tone jamming, the limiting level affects hardly on the error performance of both BPSK and QPSK signals. When limiting leveri is zero, BPSK and QPSK signals show the best error rate performance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.41-44
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• 2004

A RFID(Radio Frequency IDentification) system Is a kind of Radio Frequency Communication System and a branch of Automatic Data Collection System. The RFID System is composed of RF Tag(or Transponder) and RFID Reader(controller). This paper deal with Wireless communications that acquired RF Tag ID by RFID reader, and then target system will transmit Tag ID to RFID Server through the internet using Wireless LAN. The RFID system of Todays are commonly used by a wired RFID system. In this system uses commonly used Wireless LAN, and then we can connect the internet if we have a AP(Wireless Lan Access Point). Internet connection can make a transmission of RF Tag ID, and can make a reception of returning data that are images or information.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.229-231
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• 1994

For the effective use of satellite communication transponder, tests for the payload system such as IOT(In-Orbit Test), RPM(Routine Payload Monitoring), CSM(Communicatios System Monitoring), and REV(Remote Earth-Station Verification) have to be conducted. Those tests are used in order to verify the condition and generic design of the satellite, to provide a database for operational calculations, and to maintain the quality of communication services. As the satellite communication system gets with wider expansion with higher complexity of operation, tests for the communication system also need more complex operation that usesophisticated computer-controlled measuring system. For and C language based measurement functions, which uses GPIB protocol and SCPI commands. But SICL requires knowledge of BASIC and C language as well as GPIB and SCPL system. This paper introduces a new language called CALSTEP-Control and Access Language for the Systems of Test Equipment and Payload. This language is designed for the operator to perform the tests for the satellite communication system without any special knowledge that is mentioned above. This language has very limited number of commands which are to be used to control the payload system and test equipments to perform IOT and CSM, and those commands are very readable and easy to understand, so an operator without any knowledge of BASIC and C programming language, or SICL and SCPI command can use it.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.37-40
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• 1999

ETRI has successfully completed and delivered to KARI the KOMPSAT Mission Control System. This system was designed to work in the conventional TT&C modulation scheme with the pre-assigned frequencies. As a way to accelerate in catching up with future TT&C technology evolutions, a preliminary study needs to be carried out to prepare for the development of a spread spectrum applicable to TT&C. A brief study was carried out to review some points to be considered in designing and implementing spread spectrum schemes to the ground TT&C system intended for a LEO spacecraft. Also a simulation and link design revisit was performed to see the operational and technical benefits with the KOMPSAT TT&C parameters. An experiment concept is proposed to test as many functions at a time once the prototype is developed. In this configuration, a ground-model TT&C transponder is connected via LAN to the ETRI-developed KOMPSAT S/W simulator and linked to the KOMPSAT TM/TC processing s/w via spread spectrum signals through a GEO satellite bent-pipe link. A satellite data relay link simulation could be carried out in this configuration.

• Journal of the Korea Society of Computer and Information
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• v.20 no.7
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• pp.33-40
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• 2015

The time slot assignment problem (TSAP) or Satellite Communications scheduling problem (SCSP) for a satellite performs $n{\times}n$ ground station data traffic switching has been known NP-hard problem. This paper suggests $O(n^2)$ time complexity algorithm for TSAP of a satellite that performs $n^2{\times}n^2$ ground station data traffic switching. This problem is more difficult than $n{\times}n$ TSAP as NP-hard problem. Firstly, we compute the average traffic for n-transponder's basic coverage zone and applies ground station exchange method that swap the ground stations until all of the transponders have a average value as possible. Nextly, we transform the D matrix to $D_{LB}$ traffic matrix that sum of rows and columns all of transponders have LB. Finally, we select the maximum traffic of row and column in $D_{LB}$, then decide the duration of kth switch mode to minimum traffic from selected values. The proposed algorithm can be get the optimal solution for experimental data.