• 한국전자통신학회논문지
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• 제2권3호
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• pp.143-149
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• 2007

본 발표문에서는 게기착륙시스템이 항공기에 제공하는 유도신호의 기본원리인 공간변조에 대해서 논의함으로써 계기착륙시스템을 심도있게 이해하는데 도움이 되고자 하였다. 우선적으로 공간변조의 기본개념을 설명하였으며, 이와 함께 공간 변조된 신호가 항공기 수신기에 영향을 주어 방위각 및 활공각이 표시되기까지 전반적인 과정을 DDM(difference in depth of modulation) 및 항공기 수신기의 동작원리와 관련시켜 설명하였다.

• 한국정보통신학회논문지
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• 제25권3호
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• pp.427-432
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• 2021

본 논문에서는 미상의 통신신호에 대한 자동 변조 인식을 위하여 심층신경망인 딥뉴럴네트워크를 적용하여 변조 형태를 식별하고 그 성능을 분석하였다. 신경망 입력 데이터는 변조된 신호의 시간영역 디지털샘플 데이터, FFT(Fast Fourier Transform)를 적용한 주파수영역 데이터, 시간 및 주파수영역 혼합데이터를 사용하여 각각의 변조인식 성능을 확인하였다. 아날로그 변조 및 디지털 변조 신호 11종에 대하여 -20~18 dB 까지 다양한 SNR(Signal to Noise Ratio) 환경에서 변조인식 성능을 확인하고 그 성능을 분석하였으며, 입력 데이터의 종류에 따른 학습 속도를 확인함으로써 제안한 방법이 실제적인 자동변조 인식 시스템 구축에 효과적인 방법임을 확인 하였다.

• ETRI Journal
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• 제25권5호
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• pp.418-421
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• 2003

We propose an unbiased signal-to-interference ratio (SIR) estimator for the high speed downlink packet access (HSDPA) system. The proposed SIR estimator solves the problem of underestimation present in conventional SIR estimators and is suitable for channel quality measurement in the adaptive modulation and coding scheme of HSDPA, which requires accurate SIR estimation for optimum adaptive modulation and coding selection. Our analysis and simulation results demonstrate the improved estimation performance of the proposed SIR estimator.

• 대한전자공학회논문지
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• 제8권4호
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• pp.7-16
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• 1971

쌍트란지스터 회로에 의하면 전류제어형의 부성저항소자가 가능하다. 이와같은 부성소자를 사용한 구형파발진회로의 바이어스전류에 신호파를 중첩함으로써 펄스폭변조회로를 구성하였다. 신호파가 정인 경우에는 한쪽의 트란지스터의 바이어스전류만을 증가시키고, 또 신호파가 부인 경우에는 다른 한쪽의 바이러스만을 증가시키는 방법을 채택하였다. 따라서 신호회로로서 일종의 전파정류회로의 변형을 채용하였다. 발진주기의 이론적해석과 회로정수결정의 설계지침을 구명하고 실험회로를 제시하였다.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.65-70
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• 2008

Capacitive position sensing with modulation technique is widely used in electrostatic actuator applications. To maximize the electrostatic force and the position-sensing gain, capacitors for driving and capacitors for sensing are shared, i.e, after applying the driving voltage with high-frequency modulating signals using op amps, the position is demodulated from the modulated signal. In high-voltage applications, however, low bandwidth of a high-voltage op amp hinders adding the high-frequency modulating signal to the driving voltage. In this paper, new and very simple driving and sensing method is proposed, in which the pulse-width modulated driving voltage eliminates the need of the high-frequency modulating signal for position sensing. This new algorithm is proved by the simulation results using Matlab/SIMULINK.

• Corrosion Science and Technology
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• 제20권5호
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• pp.231-241
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• 2021

The objective of this study was to evaluate total current under steady-state conditions for a material undergoing corrosion using the electrochemical frequency modulation (EFM) technique, taking into account the presence of solution resistance and double layer capacitance. The analysis involving linearization of the Tafel curve allowed for the estimation of corrosion parameters. Results showed that the output signal was dependent on fundamental frequencies and their multiples. In addition, the output signal almost manifested itself at frequencies that were sums of fundamental frequencies of the applied sinusoidal signal. The harmonics calculated showed a significant shift from the principal frequency of input signals. The investigation involved the influence of corrosion current and anode-to-cathode Tafel slope ratio on faradaic and non-faradaic currents (including the average and RMS). The model presented showed both qualitative and quantitative improvements over the previously developed EFM technique that ignored the influence of solution resistance and the double layer capacitance while assuming the applied DC potential corresponded to the corrosion potential of the corroding material.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.77-78
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• 2006

This paper presents a signal quality estimation technique for QAM modulation systems. By making a LUT(Look-up table) putting the number of N enough, we can derive estimated SNR from LUT even though N is small. That is so called MOTM algorithm. In 16-QAM, the distance $d_a$, between adjacent symbols is always invariable, so absolute value of R(the amplitude of signal) minus $d_a$ has a always same signal distribution value. This value does not form a Gaussian shape but, by making a little bit correction, we can make this symmetrical. So, from the received symbol value, by using LUT we can easily derive the estimated SNR. By considering this, we introduce a signal quality estimation technique for QAM schemes. This proposed method can be applicable to high order modulation schemes and wide range of signal to noise ratio.

• Journal of the Optical Society of Korea
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• 제19권3호
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• pp.255-259
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• 2015

We have proposed and experimentally verified a pulse-width modulation (PWM) generator which directly generated a PWM signal in the optical domain. Output waveforms were clear at the repetition rate of 16 MHz; the duty cycle (DC) was from 14.7% to 72.1%; and the DC-control resolution was about 4.399%/dB. The PWM generator' operation principle is based on the injection-locking property of a single-mode Fabry-$P{\acute{e}}rot$ laser diode (SMFP-LD). The SMFP-LD, which has a self-locked mode wavelength at ${\lambda}_{PWM}$, was used to detect the power of the injection-locking signal (optical analog input). If the analog input power is high, the SMFP-LD is locked to the wavelength of the input signal ${\lambda}_a$ and there is no output after an optical bandpass filter (OBF). If the analog input power is low, the SMFP-LD is unlocked and there is output signal at ${\lambda}_{PWM}$ after the OBF. Thus, the SMFP-LD plus the OBF provide digital output for an analog input. The DC of the output PWM signal can be controlled by tuning the power of the analog input.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.304-308
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• 2009

This paper proposes a new concept of a signal constellation of the recently introduced half-symbol-rate-carrier phase-shift keying (HSRC-PSK) modulations for bandwidth-efficient high speed data communications. Since the HSRC-PSK modulations contain different symbol energies representing the same bit sequences due to the loss of orthogonality of their HSRC signals, it is very hard to represent the symbol using the conventional signal constellation. To resolve the problem, two different energies are assigned to represent one symbol for the HSRC offset quadrature phase shift keying (OQPSK) modulation. Similarly, the different energies exist to display the different symbol for HSRC minimum shift keying (MSK) modulation. With the proposed signal space representation, HSRC-PSK symbol can easily be shown with a two-dimensional scatter plot which provides helpful information of evaluating HSRC-PSK signal's quality.

• 전자통신동향분석
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• 제9권4호
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• pp.131-138
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• 1994

최근 무선통신의 활성화에 따라, V/UHF(very/ultra high Frequency) 대역에서 한정된 주파수를 효율적으로 이용하기 위한 방법의 하나로서, 점차 점유 주파수 대역의 폭을 축소하여 보다 많은 이용자를 수용하도록 무선 채널의 협대역화가 추진되고 있다. 본 고에서는 먼저 V/UHF 대역 무선 통신에서 채널의 협대역화에 관련된 기술 중에서 현재까지 사용되고 있는 FM(frequency modulation), AM(amplitude modulation) 변조 방식의 장,단점을 살펴본후, 새로운 LM(linear modulation) 변조 방식에 대한 기술적 배경 및 특성을 알아보았다. LM은 SSR(single side band)-AM이 발전한 것으로서, TTIB(transparent tone-in-band), CLT(Cartesian loop transmitter), FFSR(feed-forward signal regeneration), DSP(digital signal processing)등 4가지의 기술이 결합하여 만들어진 것이다. LM 방식에 사용된 4가지 기술을 소개하고, 기존의 변조 방식에 비해 개선된 사항에 대해 서술한다.