• Proceedings of the KIEE Conference
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• summer
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• pp.325-326
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• 2004

전력선통신(PLC: Power Line Communication)은 기존의 전기선을 이용하여 별도의 전용선 설치 없이 통신이 가능한 기술로서 효율적인 PLC 통신을 위해서는 가장 기본적인 기저대역의 송, 수신부상 의 원활한 데이터 전송이 이루어져야 한다. 본 논문에서는 확산대역방식의 PLC통신시스템의 수신부의 핵심모듈인 정합필터를 HDL(hardware description language)을 이용한 디지털 하드웨어인 에 위한 디지털 하드웨어인 FPGA(Field Programmable Gate Array)클 이용하여 구현하였다. 즉, 본 논문에서는 BPSK(Binary Phase Shift Keying) 변조 및 256칩 확산코드를 이용한 확산변조파형에 대한 디지털 정합필터를 FPGA로 구현하고 상관특성을 확인함으로서 모의실험상의 파형과 구현된 하드웨어상의 상관파형이 일치함을 확인하였다.

• The KIPS Transactions:PartC
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• v.11C no.3
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• pp.395-400
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• 2004

Being aware of growing needs for wireless communication led to the development of UWB systems, this study proposed an impulse for single band UWB systems which does not count a carrier; analyzed the characteristics and the problems of pulses suggested by the existing poise of the Un system; finally, proposed TDMG(Time Delay Multiple Gaussian) pulse that generates signals of UWB without attenuation of pulse width. The hardware structure of the TDMC pulse for the single band UWB system was modelled after describing the pulse in a mathematical method in an attempt to compare with performances of the existing pulses through computer simulation. The outcome of the test unveiled the fact that each center frequency of the TDMG pulse rose approximately 1GHz, and also each l0dB fractional bandwidth of the TDMG pulse was widened over 1GHz. In the case of derivative, center frequencies of the TDMG pulse rose over 1GHz each. As a consequence, the TDMG pulse appeared to have better quality frequency, satisfying the characteristics of spectrum and the band of frequency recommended by the FCC and decreasing interference with other wireless communication systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.254-262
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• 2013

This paper proposes FMT(Filtered Multi-Tone)-based digital radio implementation algorithms and the results obtained by various field tests especially in terms of transmitter characteristics. In this study, we predefined frame structure and protocols used for the CSTDMA(Carrier Sensing Time Division Multiple Access) scheme, designed digital filters and RF front end to fulfill the system characteristics such as the spectral mask and processing delays given by the Recommendation ITU-R M.1842-1. The proposed system supports exchange of data for e-Navigation with the usage of wider channel of 50-100kHz bandwidth, Turbo coding and FMT modulation. Furthermore, the common Ethernet protocol makes connection to local WLAN(Wireless Local Area Network) on board the ship for other data services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11C
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• pp.694-701
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• 2011

This paper addresses a synchronization technique based on an adaptive combining of the sub-correlation functions obtained from multiband sine phased binary offset carrier (BOC) signals, allowing a BOC signal receiver to deal with multiband sine phased BOC signals. Specifically, we first obtain the sub-correlation functions composing the BOC autocorrelation function, and then, re-combine the sub-correlation functions generating a correlation function with no side-peak. Finally, by replacing the BOC autocorrelation with the correlation function with no side-peak in the delay lock loop, the proposed scheme performs unambiguous signal tracking. The proposed synchronization scheme is applicable to generic sine phased BOC signals. Numerical results demonstrate that the proposed scheme provides a performance improvement over the conventional unambiguous schemes in terms of the tracking error standard deviation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.35-40
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• 2011

We have studied the impact and bending characteristics of a dual band antenna (1.575, 2.645 GHz) with composite sandwich construction. Mechanical performance of the antenna can be improved by reinforcing the antenna by sandwiching the planar antenna with layers of carbon fiber-reinforced plastic(CFRP) and glass fiber-reinforced plastic(GFRP) using an adhesive film. According to the ASTM D7137, ASTM C393 and MIL-STD401B, impact and bending test were performed and the S-parameters and gains of the antenna were measured in order to verify electrical and mechanical performance. The maximum contact load and the bending load of the antenna are 4 kN and 400 N and gains of the antenna are 6 dBi and 4.6 dBi in the GPS and DMB bands, respectively. The proposed antenna structure can be applied to surfaces of vehicles.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.473-476
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• 2018

Herein, a $2{\times}2$ subarray antenna is designed to implement a VHF band active electronically scanned array. The Yagi-Uda antenna is used as a radiating element. The bandwidth enhancement and miniaturization of the Yagi-Uda antenna are achieved by optimizing the diameter of a driven element and the length of a director. In addition, the grid reflector is utilized to improve the front-to-back ratio(FBR) and to reduce both the wind resistance and overall system weight. The fabricated $2{\times}2$ subarray antenna fully covers the VHF target band($0.98{\sim}1.02f_c$). The measured maximum gain is 10.61 dBi and the FBR is larger than 26 dB.

• Journal of Satellite, Information and Communications
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• v.11 no.3
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• pp.12-17
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• 2016

ICAO (International Civil Aviation Organization) recommends the introduction of SBAS (Satellite Based Augmentation System) in 2025, which provides GNSS (Global Navigation Satellite System) correction data and the ranging signal via GEO (geostationary earth orbit) satellites to GNSS users. In this paper, we present the basic design results of the satellite communication system RF link for the Korean SBAS systems, KASS (Korea Augmentation Satellite System) which is going on the development & implementation. KASS RF link was designed in consideration of both the C-band and Ku-band uplinks to meet the international standard requirements for the SBAS system, and identified the minimum EIRP and G/T performance of the KASS uplink station for each frequency band. These analysis results for the RF link design are expected to be used for an effective design of the subsystem specifications for KASS satellite communication system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.80-83
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• 2017

In this paper, the X-band reconfigurable frequency selective surface having flexible geometry was proposed. The proposed RFSS is composed of patterns of cross-shaped loop with inductive stub, which can control the frequency response for C-Band and X-band by ON/OFF state of PIN diode. To minimize the parasitic effect and to obtain the high level of isolation between the unit cell of FSS and the bias circuit, we designed the grid type bias line on bottom layer through via hole. The measured transmission characteristics show good agreement with the simulation results and good stability of frequency response for different incident angles and curvatures of surface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.4
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• pp.380-386
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• 2014

In this paper, a higher-order mode coupler using coaxial-structure waveguide for Ku-band monopulse satellite tracking is proposed. The proposed higher-order mode coupler is built in a coaxial structure for compactness and weight reduction, making it suitable for mobile tracking systems. The inner circular waveguide of coaxial-structure is used to extract the fundamental mode signal and the high-order mode signal is extracted from the four slots of the outer circular waveguide and then transmitted via given stepped rectangular waveguide structure. The simulated results show that proposed higher-order mode coupler covers 250 MHz(12.75 GHz ~ 13.00 GHz) bandwidth with return loss and insertion loss characteristics. The antenna patterns of fundamental mode and higher-order mode applicable to monopulse tracking are generated successfully. Designed higher-order mode coupler using coaxial waveguide structure for Ku-band is expected to be used for high precision monopulse satellite tracking systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.11
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• pp.955-965
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• 2013

The joint tactical information distribution system (JTIDS) is used as the communication terminal of Link-16 by the United States armed forces, north atlantic treaty organization (NATO), and other allied forces. A portion of Link-16 frequencies may be shortly remapped to other systems owing to the growing demand for frequencies, especially in civil aviation, which is witnessing a constant increase in air traffic. This will affect the performance of Link-16. Therefore, in this paper, we analyze the effect of frequency band reduction on the performance of Link-16 waveform under partial-band noise jamming with Nakagami fading, via simulation and numerical analysis. The multi-net and anti-jamming performance of Link-16 with frequency remapping is compared with that of conventional Link-16 systems. The results show that the performance of Link-16 waveform is degraded with the reduction in frequencies. Nonetheless, Link-16 retains its jam resistance, and it can support multiple users in the same time slots.