• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.507-511
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• 2010

Digital radio frequency memory (이하 DRFM)은 입력되는 RF신호를 저장 후 필요한 시점에 입력된 RF신호로 복원하여 출력하는 기능을 가진 장치로써 Jammer, EW시뮬레이터, Target Echo Generator 등 사용되는 분야가 광범위하다. 본 논문에서는 고주파 입/출력모듈, 국부 발진모듈로 구성된 고주파부와 디지털 처리부로 이루어진 DRFM의 하드웨어적 구현 방안을 제안한다. 그리고 펄스형태의 RF신호를 양자화하는 ADC(A/D conversion), 이 데이터를 저장하고 재생신호를 생산하는 FPGA와 RF 신호를 생산하는 DAC(D/A conversion)로 구성되는 디지털 처리부에서 복제된 신호 생성방안을 제안한다. 이렇게 제안된 방안을 적용하여 제작한 후 모의 신호를 입력하여 얻은 시험결과를 통하여 이 제안방안의 타당성을 확인한다.

• 한국전자파학회논문지
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• 제23권11호
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• pp.1280-1287
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• 2012

3.2~6.5 GHz 광대역 특성을 갖는 YTO(YIG Tuned Oscillator) 모듈을 설계 및 제작하였다. 위상 잡음 특성을 개선하기 위해 샘플링 믹서를 이용한 offset PLL(Phase Locked Loop) 구조로 설계하였다. 이 방식은 샘플링 믹서, 위상 비교기, 루프 필터, 전류 드라이버 회로, YTO로 구성된다. 측정 결과, 4.5 GHz에서 위상 잡음은 수식으로 도출한 값과 유사한 10 kHz offset 주파수에서 -100 dBc/Hz를 얻었다. 제작된 YTO 모듈의 위상 잡음은 동작 주파수 대역에서 기존 PLL 구조에 비해 10 dB 이상 우수함을 확인하였다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.107-110
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• 2005

This paper describes the design and fabrication of synchronous clock recovery module for S-DMB Gap Filler. Using the 2.304MHz TTL signal from gap filler tuner, clock recovery module with 10MHz output frequency including holdover function is designed. The measured performance of the clock recovery module shows a stability of less than 0.01ppm, 29 sec stability time, 10 sec holdover time, and maximum -113dBc/Hz@100Hz phase noise.

• Journal of Information Processing Systems
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• 제15권2호
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• pp.449-456
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• 2019

SMART home is one of the most popular applications of Internet-of-Things (IoT) technologies, which is expanding in terms of range of applications. SMART home technology provides convenience at home by connecting household appliances to a single network, control, and management. However, many general home appliances do not support the network functions yet; hence, enjoying such convenient technology could be difficult, and it could be expensive in the beginning to build the framework. In addition, even though products with SMART home technologies are purchased, the control systems could differ from device to device. Thus, in this paper, we propose a SMART home framework, called an S-mote that can operate all the IoT functions in a single application by adding an infrared or radio frequency module to general home appliances. The proposed framework is analyzed using four types of performance tests by five evaluators. The results of the experiment show that the SMART home environment was implemented successfully and that it functions appropriately, without any operational issues, with various home appliances, including the latest IoT devices, and even those equipped with an infrared or radio frequency module.

• 한국전자파학회논문지
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• 제18권5호
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• pp.511-521
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• 2007

본 논문에서는 복합 소형화된 Ka-대역 주파수 합성기 모듈을 제작하였다. 본 논문을 통하여 소형화 구성시 배치 방법과 체계적인 검증 방법을 제시하였다. 제작된 주파수 합성기는 X-대역 전압 제어 발진기(VCO: Voltage Controlled Oscillator)의 주파수를 3체배하여 구성하였으며, 제작된 모듈은 500 MHz 주파수 가변 범위와 약 14 dBm의 출력 전력, 그리고 100 kHz 오프셋 주파수에서 -96.17 dBc/Hz의 위상 잡음 특성을 보여주고 있다.

• Journal of Astronomy and Space Sciences
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• 제27권2호
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• pp.145-152
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• 2010

In this paper, we developed a local oscillator (LO) system of millimeter wave band receiver for radio astronomy observation. We measured the phase and amplitude drift stability of this LO system. The voltage control oscillator (VCO) of this LO system use the 3 mm band Gunn oscillator. We developed the digital phase locked loop (DPLL) module for the LO PLL function that can be computer-controlled. To verify the performance, we measured the output frequency/power and the phase/amplitude drift stability of the developed module and the commercial PLL module, respectively. We show the good performance of the LO system based on the developed PLL module from the measured data analysis. The test results and discussion will be useful tutorial reference to design the LO system for very long baseline interferometry (VLBI) receiver and single dish radio astronomy receiver at the 3 mm frequency band.

• Journal of Communications and Networks
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• 제18권2호
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• pp.201-209
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• 2016

In wireless sensor networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN medium access control protocols are bound by the energy-latency tradeoff. To break through the tradeoff, we propose a radio wave sensor called radio frequency (RF) wakeup sensor that is dedicated to sense the presence of a RF signal. The distinctive feature of our design is that the RF wakeup sensor can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF wakeup sensor a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF wakeup sensor detects a communication signal. According to our analysis, the response time of the RF wakeup sensor is much shorter than the minimum transmission time of a typical communication module. Therefore, we apply duty cycling to the RF wakeup sensor to further reduce the energy consumption without performance degradation. We evaluate the circuital characteristics of our RF wakeup sensor design by using Advanced Design System 2009 simulator. The results show that RF wakeup sensor allows a sensor node to completely turn off their communication module by performing the around-the-clock carrier sensing while it consumes only 0.07% energy of an idle communication module.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1346-1349
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• 2002

This paper presents the design and implementation of 16-QAM modem that can be applied to fixed broadband wireless access systenm. It is implemented in the hardware prototype that consist of FPGA(Field Programmable Gate Array) for digital signal processing and analog front end module for analog signal processing. We provide 20.48Mbps data rate using implemented modem and test the modem in KOREA 26㎓ broadband wireless local loop system including IFU(Intermediate Frequency Unit) and RFU(Radio Frequency Unit) via air interface.

• 한국산업정보학회논문지
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• 제9권2호
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• pp.89-95
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• 2004

CDMA(Code Division Multiple Access)는 이동통신에서 다수의 사용자들이 동시에 시간과 주파수를 공유하며 접속이 가능한 다중접속(Multiple Access) 방식의 하나이다. 그렇지만 이동통신은 주파수라는 한정된 자원을 이용하기 때문에 용량이 제한된 가용 주파수 자원을 여러 사람이 효율적으로 공유할 수 있도록 하는 다중접속이 이동통신에서는 필수적인 기술이다. CDMA는 홈네트워크, 군사용, 상업용뿐만 아니라 의료분야에까지도 다양하게 응용되어가고 있다. 본 논문은 기존 양면보드 방식이 아닌 PCB 8계층의 적층방식을 단면보드 회로로 구성하여 RF(Radio Frequency)특성을 유지하며, 슬롯형의 커넥터를 적용한 Cellular Band의 CDMA 모듈의 설계 및 성능 분석 결과를 제시한다.

• 한국전자파학회논문지
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• 제11권1호
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• pp.110-115
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• 2000

A K-band GaAs MMIC receiver module has been developed using 0.15 ${\mu}{\textrm}{m}$ HEMT technology process. It incorporates two front end low noise amplifiers, a double balanced diode mixer, and filters. The RF input frequency ranges 20.1 to 21 GHz and the IF output 1.1 to 2 GHz. Test results show an overall conversion gain of more than 27 dB, and less than a 2.2 dB noise figure. The image-rejection ratio greater than 21 dB has been obtained. The isolation between RF and IF ports is better than 27 dB, and between LO and IF is more than 50 dB.