• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1606-1616
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• 2004

This paper introduces a technique for generating an appropriate template signal via modeling of minimum-phase stable ARMA (Auto-Regressive Moving Average) system for coherent impulse communication systems. It has been well known that the transmitted impulse signal becomes deformed because of dispersive and resonant characteristics. Accordingly, in spite of using ideal template signal at the correlator, these impairments degrade overall performance attributed to low level of coherence. To increase the degree of coherence, our proposed scheme realizes A3U system derived by Gaussian pulse signal, which simulates the overall characteristic of transfer function in between transmit and receive wideband antennas so as to generate an appropriate template signal in a form of output. The performance of proposed scheme will be shown in results from computer simulations to verify its affirmative impact on impulse communication system with regarding several distinctively shaped antennas.

• Korean Journal of Optics and Photonics
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• v.4 no.2
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• pp.226-232
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• 1993

A broadband CARS system is constructed for shot by shot measurement of a full CARS spectrum, which consists of a frequency doubled Nd:Yag laser, broadband mode-less laser and optical multi-channel analyzer installed in a double grating monochromator. To increase the accuracy of CARS temperature measurement and get better the fitting goodness, we have measured the slit function of the detection system and determined the analytical functional form of the slit function. Accuracy of the CARS system for temperature measurement is evaluated from the difference between the best-fit temperature of CARS spectrum and temperature of thermocouple reading. The uncertainty of the temperature measurement is found to be less than 1.5% in temperature range from 300 K to 1300 K.

• Journal of Advanced Navigation Technology
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• v.2 no.2
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• pp.116-125
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• 1998

Most of modern mobile communication systems require low distortion in addition to high power and high efficiency characteristics for power amplifiers. The power amplifiers cause adjacent channel interference by intermodulation and spectral regrowth. In order to analyze the effects of the power amplifier on communication system, a 22Mcps spreaded digital modulated signal source and a ISM band power amplifier have been constructed, ACPR characteristics are simulated and measured for the RZ and NRZ encoded signals.

• Proceedings of the KIEE Conference
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• 2004.07d
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• pp.2646-2648
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• 2004

전력선 통신(Power-Line Communi-cation)에 있어서 전력선은 유선 매체임에도 불구하고 수많은 분기 및 부하접속, 그리고 상호간의 임피던스 부정합에 의해 무선 통신 채널 환경과 같은 다중 경로 페이딩 특성을 갖게 된다. 따라서 채널의 다중경로 해석이 상당히 중요하며, 실제 전력선 통신 채널 연구 분야에서 신호 송수신단 사이의 임펄스 응답 측정을 바탕으로 다중경로를 분석하는 방안이 적용되고 있다. PN 시퀀스를 이용한 광대역 임펄스 응답 측정 방식은 무선 채널 환경에 대해 개발되었으나, 현재는 무선 채널은 물론 전력선 채널과 같은 유선 채널에서도 적용되고 있다. 게다가 고압 배전선로와 같이 다중 경로를 포함하는 장거리 통신채널은 PN 시퀀스 방식이 여러 가지 면에서 효율적이다[1]. 본 논문에서는 PN 시퀀스 방식의 광대역 임펄스응답 측정 방법을 통해 고압 배전선로 채널의 다중경로 특성을 측정, 검토하고 이를 제시하였다.

• Journal of Korea Multimedia Society
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• v.6 no.2
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• pp.319-324
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• 2003

In this paper, a new wideband tunable analog element for multimedia system is proposed. The proposed active element is composed of the complementary cascode circuit which can extend transconductance of an element. Therefore, the unity gain frequency which is determined transconductance is increased than that of the conventional element. And then these results are verified by the 0.22$\mu\textrm{m}$ CMOS n-well parameter simulation. As a result, the gam and the unity gam frequency are 42dB and 200MHz on 2V supply voltage. And power dissipation of the designed element is 0.32mW.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.119-128
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• 2017

In this paper, the wideband direction finding algorithm and system design method for short duration signal such as frequency hopping or burst signal is presented. The polyphase filterbank that it is possible for the near perfect reconstruction was used as a pre-processing and in each subband power measurement was performed to determine whether the presence of a signal and finally general direction finding algorithm was performed. In addition, various experiments was performed using Matlab Simulink and collected data from wideband receiver to verification of the proposed algorithm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.333-341
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• 2015

In this paper, a 0.5~4 GHz frequency synthesizer having good phase noise performance is proposed. Wideband output frequencies of the synthesizer were synthesized using DDS(Direct Digital Synthesizer) and analog direct frequency synthesis technology in order to obtain fast settling time. Also in order to get good phase noise performance, 2.4 GHz DDS clock was generated by VCO(Voltage Controlled Oscillator) which was locked by the 100 MHz reference oscillator using SPD(Sample Phase Detector). The phase noise performance of wideband frequency synthesizer was estimated and the results were compared with the measured ones. The measured phase noise of the frequency synthesizer was less then -121 dBc @ 100 kHz at 4 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.115-122
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• 2016

In this paper, wideband Ku-band downconverter was designed to receiver digital satellite broadcasting. The low-nose downconverter was designed to form four local oscillator frequencies(9.75, 10, 10.75 and 11.3 GHz) representing a low phase noise due to VCO-PLL with respect to input signals of 10.7 to 12.75 GHz and 3-stage low noise amplifier circuit by broadband noise matching, and to select intermediate frequency bands by digital control. The developed low-noise downconverter exhibited the full conversion gain of 64 dB, and the noise figure of low-noise amplifier was 0.7 dB, the P1dB of output signal 15 dBm, and the phase noise -85 dBc@10kHz at the band 1 carrier frequency of 9.75 GHz. The low noise block downconverter(LNB) for wideband digital satellite broadcasting designed in this paper can be used for global satellite broadcasting LNB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.12
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• pp.1044-1052
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• 2016

In this paper, a cavity back slot antenna with a rotated rectangular patch is proposed. The proposed antenna consists of a ground plane with cavity structure, a microstrip feed line, and a rectangular patch with slot. With a dimension of $55mm{\times}40mm{\times}10mm$, the proposed antenna has the wide bandwidth due to the cavity structure. Measured 10 dB return loss bandwidth and fractional bandwidth of the proposed antenna is 5,030 MHz(3.02~8.05 GHz) and 90.9 % at the center frequency of 5.05 GHz. The proposed antenna is designed and simulated using ANSYS HFSS v.15.0.0. The designed antenna is fabricated and tested to validate its performances.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.470-473
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• 2018

Using High-order Modulation in wideband system is sensitive to change of wireless channel environment as well as changes in ripple characteristics that can occur when baseband signals pass through RF equipment. Therefore, it is necessary to design and RF tuning that minimizes ripple characteristics change, which is difficult to implement systematically and takes a long time. In this paper, we analyze the fixed ripple characteristics of the baseband signal distored through the RF transmitting and receiving equipment. And the function of compensating the compensation filter by the modem receiver is implemented in 256 TCM. Also, it is confirmed that SNR and received sensitivity are improved by applying a digital compensation filter in a channel with poor RF equipment ripple characteristics.