• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.1
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• pp.84-92
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• 1989

The purpose of this paper is to demonstrate the effect of a FH spread spectrum communication interference in TV channels and frequency compatibility in 30-88 MHz frequency band. To calculate this interferece, the strength of electric field of TV signals is derived as a function of distance between TV transmitter and receiver. An interference model is established based upon thefield strength by using the relation between the transmitted power of FH spread spectrum communications and the distance between the TV image signals, which makes TV screen a cceptble, Simultaneous transmission of FH sprea spectrum signals and TV signals is shown to be feasible, as far as the interference level is lower than the TV image signal level by 23.5dBm. As a result of frequency analysis and experiment, the FH spread spectrum communication can be used together with TV channels.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.110-116
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• 2013

The amplification rate of a RF repeater is limited by the feedbacked signals from the same repeater. And an ICS (Interference Cancellation System) repeater has been developed to remove the feedbacked signals. The ICS repeater estimates the amplitudes and the phases of the feedbacked signals and removes the estimated feedback signals from the received input signal of the repeater. However, it requires lots of hardware complexity and this leads to the increase the cost of the repeater. Moreover, the ICS repeater can not solve the pilot pollution problems. To solve these problems, we have studied the implementation and adaptation of smart antenna system for RF repeaters. We have designed a smart antenna system with a switching beam structure in order to reduce the hardware and computational complexity. After analyzing the proposed smart antenna system, we found out that the amplification rate of the proposed repeater increases 23dB compare to the amplification rate of ICS repeater and the output SINR increases 6dB compare to the ICS repeater.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.10 s.352
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• pp.18-26
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• 2006

In this paper, we propose new beamforming algorithm which overcomes signal cancellation effect even high cross correlation existing between target and interfering signal. Using the proposed method, we show that direction of arrival (DOA) of interfering signal can be estimated using correlation matrix and the cross-correlation can be eliminated in the correlation matrix of input signal. The proposed method gives high performance enhancement compared with the spatial averaging method in our computer simulation results.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.365-372
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• 1995

A signal processing technique for interferometric fiber-optic sensors is proposed. It does not require a any special optic components such as phase modulator, $3times3$ couplers,to obtain the full sensitivity of the interferometer. Instead, it requires a reference interferometer for phase referencing and a reference mirror for intensity referencing, but intensity referencing can be done without using the r reference mirror. The new technique utilizes the frequency chirping of the laser diode to process t the sensor signal with both wide dynamic range and high sensitivity of the interferometer. It was a applied to an internal-mirrored FP interferometric temperature sensor to obtain the system noise of $4\times10^{-3\circ}C$ from I cm FP Interferometor sensor device.

• Journal of Advanced Navigation Technology
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• v.6 no.4
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• pp.318-325
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• 2002

In this paper, the effects of the interference environments on the performance of the time hopping(TH) binary PPM impulse radio(IR) system are presented. Based on the monocycle pulse available within the frequency of 3.1~10.6 GHz permitted for application by FCC, a PPM-modulated TH IR system simulator was designed and followed by the analysis of the monocycle pulse characteristics as well as the system performance. Particularly for the evaluation of the system performance, the multiple access interference and the narrowband system interference signals were considered as the interference signals. Since the narrowband system interference signal has very narrow bandwidth and very large amplitude compared with those of IR system, the analysis of the IR system performance was implemented by considering the interference power and band fraction ratio of the narrowband interference signal.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.349-356
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• 2013

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage and interference of Wi-Fi networks, and as a tradeoff between transmission power and data throughput, we propose a range-aware Wi-Fi network scheme which controls transmission power according to positions and RSSI(Received Signal Strength Indication) of Wi-Fi devices and analyze the efficiency of the proposed scheme by simulation.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.39-44
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• 2008

Wireless channel exists interference by multipath a component. Adaptation array antenna that remove this interference a component forms null point about interference signal and maximizes gains about target signal. If target signal and correlative coherent interference signal are received, there is problem that is removed from arrangement output to target signal. And, adaptation array antenna is shortcoming that is sensitive in directivity error. Therefore, in this paper, introduce each existing algorithm to solve directivity error about coherent interference, and proposed beam forming technique that minimize degree of freedom loss and damage because analyzes the problem and reduces coherent interference and directivity error.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.319-325
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• 2005

A signal processing method for white light interferometry (WLI), which performs a series of analog signal processing steps to locate the central interference fringe position at high speed: is developed and applied to a WLI temperature sensor system. We found that the new method has random walk of $0.019^{\circ}C/\sqrt{Hz}$ with good linearity. However, the temperature change in the path-matching interferometer results in drift of the measured sensor output. The temperature dependence of drift in the WLI temperature sensor system, was calculated to be $1.42{\mu}m/^{\circ}C$. It is also found that the relationship between the peak spacing in the interferogram and the spacing measured by the method can be nonlinear when the fringe spacing is comparable to the coherence length of the source.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.55-62
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• 1983

The error rate performance of phase shift Keyed(PSK) signal has been evaluated in terms of carrier-to-noise ratio(CNR), carrier-to-interferer ratio(CIR), impulsive index, and the phase difference between signal and interferer in the environment of cochannel PSK inter-ference and impulsive noise. We hays derived a general equation of the probability density function (p.d.f.) of output of coherent phase detector. And the error rate of the received binary PSK(BPSK) signal has been numerically evaluated. The graphic results show us that the best case is the situation of the signal and the inter- ferer meet with orthogonal phase.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.316-326
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• 2000

A new signal processing algorithm for white light interferometry has been proposed and investigated theoretically. The goal of the algorithm is to determine the absolute optical path length of an interferometer with very high precision (<< one optical wavelength). The algorithm features cross-correlation of interferometer fringe scans and hypothesis testing. The hypothesis test looks for a zero order fringe peak candidate about which the cross-correlation is symmetric minimizing the uncertainty of misidentification. The shot noise limited performance of the proposed signal processing algorithm has been analyzed using computer simulations. Simulation results were extrapolated to predict the misidentification rate at Signal to-Shot noise ratio (SNR) higher than 31 dB. Root-mean-square phase error between the computer-generated zero order fringe peak and the estimated zero order fringe peak has been calculated for the changes of three different parameters (SNR, fringe scan sampling rate, coherence length of light source). Results of computer simulations showed the ability of the proposed signal processing algorithm to identify the zero order fringe peak correctly. The proposed signal processing algorithm uses a software approach, which is potentially inexpensive, simple and fast.