• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.227-230
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• 2008

기존의 대표적인 디지털 통신방식으로 주파수 편이 변조(FSK: frequency shift keying), 위상 편이 변조(PSK: phase shift keying), 진폭 편이 변조(ASK: amplitude shift keying) 방식들이 있다. 본 논문에서는 디지털 통신에서 비트 전송률을 높이기 위하여 스케일링 함수(scaling function)와 웨이브릿(wavelet)을 이용한 2비트 스케일을 갖는 웨이브릿 편이 변조(WSK: wavelet shift keying)신호의 복원 알고리즘을 제안한다. 변조시 스케일링 함수(scaling function)와 웨이브릿(wavelet) 그리고 이 두 신호를 반전하여 2비트 스케일 즉, 00, 01, 10, 그리고 11로 변조하였다. 복조시에는 변조된 신호를 2개의 2진 정합필터에 통과시켰다. 그리고 정합필터를 거친 파형을 조합하여 4가지 신호를 복원하였다. 모의실험 결과 제안한 알고리즘이 기존의 웨이브릿 편이 변조 시스템에 비해 전송효율이 향상되었음을 알 수 있었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.12
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• pp.23-32
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• 2004

This research investigates the performance of the optical transmissions systems using the SSB modulation format The focus was on the spectral efficiency of the WDM systems and the transmission penalties due to the fiber nonlinearities. By investigating the performance obtained with ideal SSB signal, we set the upper limit of the performance which can be obtained by SSB technology. Furthermore, we investigated the performance obtainable with SSB signals which can be generated with realizable devices. Since SSB formats are more susceptible to the fiber nonlinearities, SSB formats exhibited inferior transmission performances compared to the DSB format. However, within the 500~1000 km transmission range, which is the focus of this research, it was found that the WDM systems with 12.5 GHz channel spacings might benefit from the SSB modulation techniques.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.233-236
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• 2001

We have designed and fabricated ASK modulator MMIC operating at 5.8GHz for OBE used in AGPS (Automatic Gate Passing System). ASK modulator MMIC was designed to apply a sing1e supply voltage of 3V to the drain in order to decrease ACP (Adjacent Channel Power). The measurement result of this chip exhibits on/off characteristic over 30dB. The design parameters are optimized through ADS simulation tool. The layouts and fabrication o( ASK Modulator MMIC were designed and fabricated by using ETRI 0.5${\mu}{\textrm}{m}$ MESFET library. The chip sizes were 1mm $\times$1mm. The performance analysis of the implemented ASK Modulator based on the design parameters is accomplished.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.11
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• pp.12-17
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• 2009

This paper presents a tag emulator for a UHF band RFID system. The tag emulator supports the 1800-6C and EPC global class 1 generation 2 standards. The transmitted signal from a reader is generated using the PIE coding and ASK modulation methods. Signals of a tag are from the FM0 coding and ASK modulation methods. The ARM7 processor carries out the overall control of the system and signal analysis of incoming data. The verification of the tag emulator employs the application platform implemented in C++. Users can define parameter values for protocol during the application run. The tag emulator presented in this paper allows evaluating various design alternatives of the target RFID system in real applications.

• The Journal of the Korea Contents Association
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• v.9 no.2
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• pp.10-17
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• 2009

This paper analyze the effect of frequency offset for the IEEE 802.15.4b LR-WPAN(Low-Rate Wireless Personal Area Network) with 915MHz bandwidth noncoherent DSSS O-QPSK based receiver system, and presents a compensation method with addition of differential filter to the system for compensation of frequency offset problem. DSSS PSSS-ASK and DSSS O-QPSK modulation techniques are accepted within the regularization of IEEE 802.15.4b. These new method can obtain 250kbps transmission rate. The DSSS O-QPSK modulation method that is used in this paper has no BER variation below 40ppm(frequency offset 36.6kHz), but if the offset frequency become high above 40ppm, then the system cannot have stable receiving condition due to worse BER. To solve this problem, we present a more stabilized receiver system at maximum frequency offset ${\pm}80ppm$ using MDDF unti a correlator of DSSS O-QPSK modulator. Moreover computer simulation results will be presented to evaluate the performance of the proposed algorithm unde various AWGN and frequency offset environment.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.443-444
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• 2008

A double-balanced frequency up-converter using the Gilbert cell structure has been designed with the TSMC $0.18\;{\mu}m$ CMOS library. The frequency up-converter consists of a Mixer core and IF / LO balun. Frequency Up-converter exhibits a 3.4 dB conversion gain with a - 7.6 dBm $P_{1dB}$ for IF power of -10 dBm and LO power of 0 dBm inputs. It also exhibits 92.2 % modulation depth as a ASK modulator.

• The Journal of the Korea Contents Association
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• v.6 no.1
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• pp.8-13
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• 2006

In this thesis, an automatic door lock system using a dual tone multiple frequency(DTMF) signal generated as pushing the key button of mobile phone is proposed and implemented. This system consists of a transmitter module and a receiver module for processing the DTMF signal of mobile phone. The DTMF signal of mobile phone connected with ear-phone jack enter into the input terminal of DTMF receiver and those are encoded by a code-converter with 4-bits binary format in the DTMF receiver. The encoded output signals are transmitted to the amplitude shift keying(ASK) modulator of transmitter module and the modulated ASK signals which are converted into radio frequency(RF) signals propagate in a free space. The RF signals passed through a free space are demodulated by the ASK demodulator of receiver module and the demodulated ASK signals are sent to a micro-controller unit(MCU). The output signals processed by the MCU are compared with the secreted identification number which is prerecorded in a microprocessor and are transferred to a power relay. If the result is the same, the automatic door lock system opens a door. In the opposite case, it maintains closing the door. The implemented automatic door lock system operates well in mobile environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.58-64
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• 2006

A 900-MHz band transceiver has been developed for RFID reader applications. In the transmitter, a GaAs SPST switch is used for high speed switching and low power consumption. In the receiver, a double balanced mixer is used to compress even-harmonic products. The ASK demodulator which consists of an active filter and comparator is used to reject the unwanted in band interferers. The transceiver produces a maximum transmitting power of 30 dBm and exhibits an 5 m communication range with a 6-dBi gain antenna.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.32-43
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• 2004

RFID 시스템에서 태그는 리더와 전자기 에너지 교환에 의해 동작을 하며 배터리를 사용하는 active 형 태그와 배터리를 사용하지 않는 passive형 태그로 크게 구분된다. 또한 태그는 자체 회로구조에 의해 harmonic 태그, anharmonic 태그, sequenced amplifier 태그로 나뉜다. Passive 태그에서는 리더의 반송파 backscatter 방식을 이용하여 동작을 하며 active 태그는 자체 발진회로에 의해 태그정보를 송신한다. 태그의 변조방식으로 PSK, FSK, ASK 등을 사용하며 변조방법에 따라 회로 구성과 프로토콜 설계가 달라진다. 또한 리더의 전파 신호를 정류하기 위하여 렉테나(rectenna)가 필요하다. 본 논문에서는 태그의 분류, 동작, 구조 등에 관한 일반적인 내용을 기술하였다. 특히 UHF 대역 이상의 태그 기술 최근 추세가 안테나 부분을 제외하고 CMOS one chip화 하는 수준으로서 900 MHz UHF 대역, 2.45 GHz RFID 칩이 상용화 되어 있다. 칩의 내부구조와 태그의 변조방식에 의거한 동작에 관한 개괄적인 내용을 서술하였다.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.428-438
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• 2021

For long-range communication in deep water, low carrier frequency is efficient due to a decrease in transmission loss. However, there is a limitation in that the data rate decreases due to a narrow bandwith. In order to increase the data rate in an environment with a limited bandwidth, it is necessary to design a higher-order modulation scheme. This paper analyzes the long-range communication data modulated by higher-order modulation schemes. The long-range communication experiment (23 km ~) was conducted in East Sea in October 2020. During the experiment, a vertical line array was utilized and communication sequences were modulated by Phase Shift Keying (PSK) and Quadrature Amplitude Modulation (QAM) schemes and transmitted by a towed source. In more detail, PSK modulation consists of quadrature PSK and 8PSK, QAM modulation consists of 8QAM and 16QAM. Time reversal processing is applied to mitigate inter-symbol interference by utilizing the correlation between received signals and channel impulse responses. All modulation schemes show successful results at 23 km range, demonstrating the feasibility of higher-order modulation in long-range communication.