• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.189-193
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• 2005

In this paper, we propose a direct conversion double-balanced down-converter fer MB-OFDM W system, which is implemented using $0.18\;{\mu}m$ CMOS technology and its measurement results are shown. The proposed down-converter adopts a resistive current-source instead of general transconductance stage using MOS transistor to achieve wideband characteristics over RF input frequency band $3\~5\;GHz$ with good gain flatness. The measured conversion gain is more than +3 dB, and gain flatness is less than 3 dB for three UWB channels. The dc consumption of this work is only 0.89 mA from 1.8 V power supply, leading to the low-power W application.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1178-1185
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• 2009

In this paper, a wideband ultra-high speed & high purity discrete frequency synthesizer having minimum 2.5 MHz step size was proposed. To achieve fast and wideband operation, discrete frequencies were synthesized by mixing of 3 different pre-synthesized 16 frequencies made from fixed PLL and frequency dividers. Frequencies with discrete 2.5 MHz step were produced in 710~1,610 MHz. The measured hopping response time was 350 nsec average, output level was 21.5 dBm average with 2.65 dB flatness, spurious and harmonics level were suppressed below -60 dBc, and phase noise was -94 dBc/Hz@100 Hz. Also, a new measurement method for synthesizer response time was described.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.9
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• pp.1285-1291
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• 2013

In this paper, a double circular ring monopole antenna for wideband applications is designed and fabricated. The proposed antenna is based on a planar monopole design, and composed of double circular ring of radiating patches and ground plane to obtain the wideband characteristics. To get the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and found the parameters that effect antenna characteristics. Using the obtained parameters, the proposed antenna is fabricated. The fabricated antenna is measured at the operating frequencies, and the return loss coefficient, gain, and radiation patterns are determined. The results of measurement, -10dB impedance bandwidth, measured return loss is 4,530 MHz(2,510-7,040 MHz) and antenna peak and average gains for the frequencies are obtained 0.71~3.38 dBi, -3.85~0.3 dBi, respectively. In case of radiation patterns, the proposed antenna displays nearly omnidirectional radiation characteristics in the E-plane, and monopole-like radiation pattern characteristics in the H-plane.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.8
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• pp.3040-3053
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• 2015

Wideband code division multiple access (WCDMA), high speed packet access (HSPA) and HSPA+ are third generation partnership project (3GPP) standards. These systems are the major wireless communication standards. In order to test the performance of WCDMA/HSPA/HSPA+ signal in a base station, the measurement hardware is required to the evaluation of the transmitted signals. In this paper, the algorithm for the performance measurement of the WCDMA/HSPA/HSPA+ is proposed. Also, the performance of the measurement algorithm is used to evaluate the generated signal by the WCDMA/HSPA/HSPA+ signal generator. Generally, the algorithm of normal modems cannot be applied to the measurement system because the signal measurement equipment needs to guarantee the high accuracy. So, the WCDMA/HSPA/HSPA+ signal measurement algorithm for the accurate measurement is proposed. By the simulation, it is confirmed that the proposed measurement algorithm has good performance compared with the specification. Therefore, the proposed algorithm can be usefully applied to verify the performance of the measurement using the simulation.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.277-286
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• 2010

In this paper we analyse radiation measurement method for UWB wireless system of the wideband low power frequency characteristics. In the radiation measurement environment we discuss RMS electric field strength, UWB PSD, UWB detect signal level, UWB noise signal collection etc.. also, we discuss power measure method of the CISPR16-1, low level e.i.r.p radiation measurement method. lastly we analyse consideration problem for the signal analyser of the UWB system.

• Journal of the Korean Institute of Intelligent Systems
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• v.27 no.2
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• pp.144-149
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• 2017

In this paper, we developed an intelligent and wideband RF-receiver module to represent a high dynamic range and good linearity characteristics up to 650MHz-2700MHz frequency band. and implemented an intelligent digital-RF- distorted signal measuring system for the RF distortion (intermodulation) signals. Broadband RF-receive module was designed to represent the optimized linear parameters of the receiver to meet the low noise and wide dynamic range. The designed intelligent digital-distortion(intermodulation) signal measument system measured by applying the 1MHz IF of third intermodulation signal of DUT and Measured data was recorded by program on the PC monitor with GUI interface. By variable up to 650MHz-2700MHz measured data showed up to -127.8dBc to -138dBc of the distortion (intermodulation) signal. And developed intelligent digital- distortion signal measurement system can be used to measure intermodulation distortion signal of wireless system widely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.765-774
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• 2013

In this paper, we present a cooperative compressed spectrum sensing scheme for correlated signals in decentralized wideband cognitive radio networks. Compressed sensing is a signal processing technique that can recover signals which are sampled below the Nyquist rate with high probability, and can solve the necessity of high-speed analog-to-digital converter problem for wideband spectrum sensing. In compressed sensing, one of the main issues is to design recovery algorithms which accurately recover original signals from compressed signals. In this paper, in order to achieve high recovery performance, we consider the multiple measurement vector model which has a sequence of compressed signals, and propose a cooperative sparse Bayesian recovery algorithm which models the temporal correlation of the input signals.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.10
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• pp.597-601
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• 2004

A high bandwidth watt-converter, based on an inexpensive, commercially available, standard IC package, is described that covers a frequency ranges from DC to 100 kHz. The new resistive shunt for a wide-band frequency current measurement of the watt-converter was developed. The converter will use application in accurate power measurement under distorted and high frequency conditions. The advantages of the proposed watt-converter are its simplicity, low cost and fast response time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.160-164
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• 2002

A special discharge cell containing a free conducting particle was used to generate the discharges in $SF_6$. The analog bandwidth of the measurement system exceeded 5 GHz. The measured signals were processed to compensate for the response of the measurement system. The discharge current rise time was in the range of 70 ps, while its full-width half-maximum was 120 ps. Single and double current pulses of positive and negative polarities were measured. Likewise, these pulses were compared with the measurement obtained using a conventional partial discharge detector of the IEC60270 type

• The Journal of Information Technology
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• v.8 no.3
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• pp.25-33
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• 2005

This paper describe a method for measuring line impedance as a function of frequency for an energized powerline in normal operation. A small sinusoidal signal of a powerline communication utility frequency 30khz$\sim$1Mhz band is continuously injected into the line, and a implemented impedance analyzer calculates the indoor powerline channel impedance from the measured magnitude and phase of resulting voltage and current. The impedance measurement is executed over a range of frequencies to produce a wideband impedance versus frequency characteristic. Implemented impedance analyzer can analysis powerline communication environments measuring line impedance due to load caused in indoor. And measured analysis information through the database can use to evaluate performance of modem and to decide test environment standard.