• International Journal of Aeronautical and Space Sciences
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• v.3 no.2
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• pp.40-45
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• 2002

A radiation analysis is performed for the Ka and Ku-band transponder of the Communications and Broadcasting Satellite (CBS) that is planned for launch into the geo-synchronous orbit. A particular attention is given to calculation of Total Ionizing Dose (TID) for the mission life time of 15 + 3 years. A numerical modeling of the charged particles at the geo-synchronous orbit is undertaken. The charged particles from the modeling are then transported through the mechanical structure and component housings of the transponder. A set of locations are selected for the detailed calculation of TID. The results from the present calculation show that three-dimensional modeling of the component housings as well as the mechanical structure of the spacecraft is requisite in order to acquire a reliable calculation of TID.

• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.60-69
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• 2015

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• ETRI Journal
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• v.25 no.5
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• pp.379-386
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• 2003

This paper presents the design of a narrow-band channel filter and its group-delay equalizer for a Ka-band satellite transponder. We used an 8th order channel filter for high selectivity with an elliptic-integral function response and an inline configuration. We designed a 2-pole, reflection-type, group-delay equalizer to compensate for the steep variation of the group-delay at the output of the channel filter, keeping the thermal stability at ${\pm}7$ ns of group-delay variation at the band edges over 15-55$^{\circ}C$. We devised a new tuning technique using short-ended dummy cavities and used it for tuning both the filter and equalizer; this removes the necessity of additional tuning after the cavities are assembled. Through measurement, we demonstrate that the group-delay-equalized filter meets the equipment requirements and is appropriate for satellite input multiplexers.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.155-160
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• 2005

We propose a tram position estimation method for automatic train control system. The accurate train position should be continuously feedback to control system for safe and efficient operation of trains in railway. In this paper, we propose the sensor fusion method integrating a tachometer, a transponder, and a doppler sensor far estimation of train position. The external sensors(transponder, doppler sensor) are used to compensate for the error of internal sensor (tachometer). The Kalman filter is also applied to reduce the measurement error of the sensors. Simulation results are then presented to verify the usefulness of the proposed method.

• Journal of Sensor Science and Technology
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• v.20 no.3
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• pp.193-198
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• 2011

In this paper, we used optoelectronic feedback to generate the carrier frequency for the ASK modulation of a lighting LED. A solar cell was used for photo-detector in the feedback circuit, and the LED light was ASK modulated by controlling the ON/OFF state of the switch that is installed in the feedback loop. The oscillation frequency of the optoelectronic feedback loop was about 50 kHz and the data rate of the ASK modulation was 9.6 kbps. In experiments, the optoelectronic feedback circuit was used for the ASK modulation of a lighting LED in the transponder of a visible light identification system, and data exchange between the transponder and the reader was successfully carried out.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.96-99
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• 2003

This paper presents the development of a Ku-band Low Noise Amplifier with the Noise figure of 1.4dBmax, the gain of 35dB, and the In/Out Return toss of -22dB/-18dB in the frequency range from 14 to 14.5GHz for Satellite transponders. All RF components were assembled using a hybrid technology with 15-mil thin-film substrates. The mechanical and thermal design of the housing was performed considering a vibration and a vacuum of space environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.507-513
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• 2002

In this paper, the receiver using Heterodyne type is designed and implemented for a pulse radar at 9.4 GHz. The If amplifier, which occupies a significant size in a Heterodyne receiver for pulse radars, can be removed. Furthermore, by using detector logarithmic video amplifier in baseband, the receiver has a small size and it's characteristic shows a high dynamic range and sensitivity. From the results of measurements, the minimum receiver power of -70 dBm and selectivity of 55 dB are obtained.

• Journal of Satellite, Information and Communications
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• v.2 no.1
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• pp.7-13
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• 2007

A new and effective Doppler effects compensation method based on constellation estimation as well as an average power saving strategy by modified modulation scheme utilizing zero point constellation are presented with theoretical analysis and relevant simulations. The suggested schemes are proved to be very effective for satellite OFDM signals relayed by power limiting transponder for the mobile terminal on high speed vehicles.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.344-346
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• 2004

KOMPSAT-2 (Korea Multi Purpose Satellite 2) which is scheduled to launch in 2005 year will communicate with KARI TTC (Tracking, Telemetry, and Command) station flying along sun synchronous orbits (685 km). The command from KARI TTC passes S-band omni-antenna, RF assembly, and transponder and finally reachs OBC (On Board Computer). The telemetry from KOMPSAT-2 arrives at KARI TTC through inverse procedure. In this paper, RF compatibility test between KOMPSAT-2 and KARI TTC station is demonstrated. RF interface for this test was established through real space and uplink signal test and downlink signal test and uplink & downlink signal test were performed.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.247-250
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• 2004

Tracking systems for launch vehicle consist mainly of radar transponder (beacon), RF switch or power divider, antennas as onboard system, and single or multiple radars as ground one. In this paper, tracking systems, which are applicable to KSLV (Korea Space Launch Vehicle)-l, are introduced and the electrical performances for developed prototypes are presented. We have also performed RF link analysis for both uplink and downlink, and estimated that the maximum distance to be able to track KSLV-l stably is dependent on uplink characteristic in our system.