• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1128-1139
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• 2013

KOMPSAT-5(KOrea Multi-Purpose SATellite-5) has a benefit of continuously conducting its mission in all weather and even night by loading SAR(Synthetic Aperture Radar) payload, which is different from optical sensor of KOMPSAT-2 satellite. During IOT(In-Orbit Test) periods, SAR image calibration should be conducted through ground target of which location and RCS is pre-determined. Differently from the conventional corner reflector, active transponder has a capability to change its internal transfer gain and delay, which allows active transponder to be shown in a pixel of SAR image with very high radiance and virtual location. In this paper, the development of active transponder is presented from design to I&T(Integration and Test).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.2
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• pp.163-171
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• 2016

In order to detect the exact position of high-speed train, it is necessary to obtain location information from the transponder tag installed along the track. In this paper, we proposed parallel descrambling scheme for high-speed railway transponder system, which aims for reducing the processing time required to decode telegram. Since a telegram is stored in a tag after information bits are scrambled by an encoder, decoding procedure includes descrambling of received telegram to recover the original information bits. By analyzing the structure of the descrambling shift register circuit, we proposed a parallel descrambling scheme for fast decoding of telegram. By comparing the required number of clocks, it is shown that the proposed scheme significantly outperforms the original one.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.393-394
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• 2007

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.20-25
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• 2012

The COMS, which is a multi-purposed satellite that provide the oceanic measurement data and meterological image data, is operating since 2010. Ka-band satellite communication transponder in COMS gets the MSM function that can provide the required multi-beam and transmits the multi-mode signal with high data rate. The phase noise of COMS communication transponder can be increased because of several local oscillators for MSM function and the utilization of Ka-band frequency. The phase noise affects the performance for the multi-mode and high rate data based- transmission method, it is not possible to recover the transmission data in system with the high system phase noise. In this paper, the phase noise of COMS was measured and the effects of the measured phase noise are analysed and evaluated in the viewpoint of the noise bandwidth of transmission system, Also the transmission performances for multi-mode and high rate data are evaluated in the presence of COMS phase noise.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1204-1211
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• 2012

Measurement and analysis results of the extracted radiation-patterns from the field-experiments which were conducted to acquire the generic technology for calibration and validation of the satellite SAR system(Synthetic Aperture Radar) are presented in this study. Prototype of active transponder is adjustable within maximum 63.1 dBsm of RCS (Radar Cross Section) and includes the receiving-function with external receiver. To increase an accuracy of these field experiments, we repetitively measured satellite SAR systems of the same operating mode(i.e., COSMO-SkyMed No. 2 & 3, hh-pol., strip-map himage mode, 3 m resolution). Then, the reliability of experimental results was cross-checked through analysis of the RCS of active transponder on SAR image. The property of azimuth radiation patterns of satellite SAR system extracted from them has $0.352^{\circ}$ of HPBW(half-power beamwidth), $0.691^{\circ}$ of FNBW(first-null beamwidth), and 11.17 dB of PSLR(peak to side lobe ratio), respectively.

• Journal of Sensor Science and Technology
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• v.20 no.6
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• pp.412-419
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• 2011

In this paper, we used the inter-bit noise detection method in order to reduce the effects of noise light in a visible light identification system that uses a visible LED as a carrier source. A visible light identification system consists of a reader and a transponder. When the enable signal from the reader is detected, the transponder encodes the response data in RZ(Return-to-Zero) bit stream and sends response signal by modulating a visible LED. The reader detects the response signal mixed with noise light, samples the noise voltage in each blank low time between data bits of the RZ signal, and recovers the original data by subtracting the sampled noise from the received signal. In experiments, we improved the signal-to-noise ratio by 20dB using the inter-bit noise detection method.

• 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.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.602-611
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• 2017

In railway systems, the exchange of information between running trains and wayside equipment is a very important role in various applications such as position detection and train control. Track circuits have been used as the medium for information transmission between trains and wayside. However, track circuits must be installed continuously along the track on the ground, resulting in an inevitable increase in installation and maintenance costs. One of the most promising solutions to reduce these costs is to mix continuous information transmission (via wireless communication) and discontinuous information transmission (via transponder). In this study, we designed antennas of railway high-speed transponder readers and tags for wireless power transmission, which can be used to transmit information from ground to high-speed trains with a maximum speed of 400km/h. We also verified system performance through computational simulation and prototyping.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.235-238
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• 2002

In this paper we describe the design and implementation of Electrical Ground Support Equipment(EGSE) for the CBS transponder testing. The main task of EGSE is to check out satellite systems, at system or subsystem level, during integration and validation phases of their life-cycle. Through a combination of hardware and software elements, EGSE supports manual, semi-automatic and fully automated testing. Automation is achieved by offering users simple, yet powerful means to write their own test application programs (test sequences) in high-level, test-oriented language and to run them in a strict real-time environment. The core of this environment is a user-configurable real-time database, containing all the information needed to calibrate acquired data, check them against predefined thresholds, automatically react to out-of-range conditions, display data using animated graphics or synoptic windows, and so on.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.9-15
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• 2020

In this paper, we propose a case that drone (unmanned aerial vehicle), one of the representative technologies of the 4th Industrial Revolution, threatens airport safety and privacy infringement, and describes a drone control system proposal to solve the problem. Unmanned aerial vehicle (Drone) is creating a serious problem recently, In Korea, on May 21, 19, according to the Jeju Regional Aviation Administration, drones flew over Jeju Jeongseok Airfield twice in the same month, causing problems in aircraft operation. In overseas cases, two drones near the runway of Gatwick International Airport in the UK There has been a disturbance in which the takeoff and landing of the aircraft flies for a while, and various problems have occurred, such as voyeuring the private life of an individual using a drone. This paper is equipped with an Acess Point transponder mounted on a drone (unmanned aerial vehicle), and unspecified many who want to receive flight information (coordinates, altitude, and obstacles) of the drone access the drone AP, receive and receive the flight information of the drone, and receive unspecified multiple Drone AP flight information is collected and collected to provide the information of the drone currently floating on one user interface screen. In addition, an AP transponder is proposed to operate a safe drone (unmanned aerial vehicle) and the drone's flight information is transmitted., To receive and collect and collect data.