• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.219-226
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• 2007

In this paper, we report phase noise effects on SER(Symbol Error Rate) of MQAM(M-ary Quadrature Amplitude Modulation), DPSK(Differential Phase Shift Keying), OFDM(Orthogonal frequency Division Multiplex)-MQAM and OFDM-DPSK. SER of each modulation method has been quantified at the various offset frequencies of the local oscillator and compared with phase noise effects with the ideal cases, which have no phase noise, through the MATLAB simulation. And the ratio of modulation bandwidths to the SERs at the various frequency offsets for the above modulation methods have been analyzed for the system requirement of minimum phase noise characteristics.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.131-136
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• 2010

Modification of the phase gradient formulation is proposed in order to make phase retrieval less susceptible to noise. The modified formulation is derived from separation of the phase terms and the intensity modulation terms of interferograms, and subsequent differentiation to reduce the noise-induced error of the phase gradient vector. Its performance is evaluated and compared to that of the conventional formulation, and noise-robust nature is confirmed.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.5
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• pp.673-680
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• 2017

In the proposed paper, we designed low noise frequency synthesizer with compact size for Multi-Band. The proposed frequency synthesizer consists of fundamental frequency band(2 GHz) and harmonic frequency band(4 GHz). To improve the phase noise and spurious level of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise and design the multi-band's structure. The implemented frequency synthesizer reduce both the phase noise and spurious level. The phase noise is -92.17 dBc/Hz at 1 kHz frequency offset in 2 GHz and -90.50 dBc/Hz at 1 kHz frequency offset in 4 GHz. All spurious signals including fundamental frequency are suppressed at least 20 dBc than the second harmonic frequency.

• The Journal of the Acoustical Society of Korea
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• v.20 no.7
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• pp.13-20
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• 2001

The active noise cancellation system offers a better low frequency performance with a smaller and lighter system compared to a passive one. This paper presents an active noise control system capable of reducing the noise in a helmet after attenuating the external noise using the helmet as the passive noise reduction system, which consists of a controller for inverting and compensating the phase delay, a microphone for picking up the external noise, and a loudspeaker for radiating the acoustic anti-phase signal to reduce the external noise. In this paper, external noise can be reduced by noise controller by compensating the phase difference to be 180°in the frequency of maximun value in the amplitude response. The noise of the phase delay covered from 50°to 310°was reduced in this system and it is possible to obtain a noise reduction of up to approximately 20 dB at the ears in the enclosure.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.10
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• pp.455-460
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• 2005

A simple construction and low cost, fault tolerant power electronic drive has made the switched reluctance drive a strong contender for many applications. But, switched reluctance drive does exhibit higher levels of vibration and acoustic noise than that of most competing drives. The main source of vibration in the switched reluctance drive is generated by rapid change of radial magnetic force when phase current is extinguished during commutation action. In this paper,2 excitation method is proposed and compared to reduce vibration and acoustic noise of the switched reluctance drive. The excitation strategies considered this research are 1-phase, 2-phase and hybrid excitation method. 1-phase method is a conventional and 2-phase method is excited 2 phases simultaneously. The hybrid excitation has 2-phase excitation by long dwell angle as well as conventional 1-phase excitation. The vibration and acoustic noise are compared and tested. Suggested 2-phase and hybrid strategies reduce acoustic noise because the scheme reduces abrupt change of excitation level by distributed and balanced excitation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.2
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• pp.53-58
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• 2004

In this paper, the low-phase dual-band VCO, by adding switching circuit with PIN diode at feedback loop of the oscillation part having negative-resistance, is realized. In order to reduce the phase noise of the VCO, PBG structure applied to the ground plane of the resonator. When applying for PBG structure, output power is -9.17㏈m and phase noise is -102㏈c/Hz at 5.25㎓, output power is -5.17㏈m and phase noise is -101㏈c/Hz at 1.8㎓, respectively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.20-25
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• 2012

The COMS, which is a multi-purposed satellite that provide the oceanic measurement data and meterological image data, is operating since 2010. Ka-band satellite communication transponder in COMS gets the MSM function that can provide the required multi-beam and transmits the multi-mode signal with high data rate. The phase noise of COMS communication transponder can be increased because of several local oscillators for MSM function and the utilization of Ka-band frequency. The phase noise affects the performance for the multi-mode and high rate data based- transmission method, it is not possible to recover the transmission data in system with the high system phase noise. In this paper, the phase noise of COMS was measured and the effects of the measured phase noise are analysed and evaluated in the viewpoint of the noise bandwidth of transmission system, Also the transmission performances for multi-mode and high rate data are evaluated in the presence of COMS phase noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4334-4356
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• 2017

In orthogonal frequency-division multiplexing (OFDM) systems, phase noise introduced by the local oscillators can cause bit error rate (BER) performance degradation. To solve the phase noise problem, a novel orthogonal-polarization-based phase noise self-cancellation (OP-PNSC) scheme is proposed. First, the efficiency of canceling the phase noise of the OP-PNSC scheme in the AWGN channel is investigated. Then, the OP-PNSC scheme in the polarization-dependent loss (PDL) channel is investigated due to power imbalance caused by PDL, and a PDL pre-compensated OP-PNSC (PPC -OP-PNSC) scheme is proposed to mitigate the power imbalance caused by PDL. In addition, the performance of the PPC-OP-PNSC scheme is investigated, where the signal-to-interference-plus-noise ratio (SINR) and spectral efficiency (SE) performances are analyzed. Finally, a comparison between the OP-PNSC and polarization diversity scheme is discussed. The numerical results show that the BER and SINR performances of the OP-PNSC scheme outperform the case with the phase noise compensation and phase noise self-cancellation scheme.

• ETRI Journal
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• v.23 no.4
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• pp.199-201
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• 2001

The phase noise reduction in a configuration of the HEMT oscillator with a dielectric resonator coupled by a quarter-wavelength impedance inverter is investigated. Two HEMT oscillators for a satellite payload system are manufactured in the same configuration except for the coupling configuration of the dielectric resonator (DR) in order to empirically demonstrate the phase noise reduction. Experimental result shows that a phase noise reduction by 14 dB can be enhanced by increasing the characteristic impedance of a coupling microstrip impedance inverter.

• Journal of electromagnetic engineering and science
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• v.16 no.3
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• pp.191-193
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• 2016

This paper proposes a voltage-controlled oscillator (VCO) that has broadband turning and low-level of phase noise characteristics. Due to the micro-strip line resonant circuit with a low Q value, which is applied to the broadband tuning range, the depreciated phase noise performance is compensated by restraining the harmonics of the oscillating frequency. The VCO was designed according to the proposed structure as well as the conventional structure, and the superiority of the proposed structure was verified through its simulation, fabrication, and measurement.