• Journal of electromagnetic engineering and science
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• v.6 no.2
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• pp.103-109
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• 2006

This paper suggests an efficient and comprehensive algorithm of the protection ratio derivation and illustrates some calculated results applicable to the initial planning of frequency coordination in the fixed wireless access networks. The net filter discrimination associated with Tx spectrum mask and overall Rx filter characteristic has been also examined to show the effect of the adjacent channel interference. The calculations for co-channel and adjacent channel protection ratios are performed for the current microwave frequency band of 6.7 GHz including Tx spectrum mask and Rx filter response. According to results, fade margin and co-channel protection ratio reveal 41.4 and 75.2 dB, respectively, for 64-QAM and 60 km at BER $10^{-6}$. It is shown that the net filter discrimination with 40 MHz channel bandwidth provides 28.9 dB at the first adjacent channel, which yields 46.3 dB of adjacent channel protection ratio. In addition, the protection ratio of 38 GHz radio relay system is also reviewed for millimeter wave band applications. The proposed method gives some advantages of an easy and systematic extension for protection ratio calculation and is also applied to frequency coordination in fixed millimeter wave networks.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.4
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• pp.37-42
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• 1984

In this paper, effective methods of symbol timing in a 9600 bps modem are presented. The symbol timing circuit consists of a square-low device followed by a high-Q narrow band-pass filter tuned to a symbol frequency. Also, the advantages of using a digital phase-tooted loop (DPLL) to suppress side tones are described, and statistical properties of timing wave are derived. In addition, the overall performances of the symbol timing circuit are verified by computer simulation.

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.101-107
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• 2004

This paper describes the digital back-end system for getting the data to analyze the user observation mode by digitalize the analog data after receiving the space radio using the radio telescope, The received analog data will be digitalized by high-speed sampler with 1 Gsps for 4 channel frequency band of millimeter wave, and the digital data will be transported through the fiber-optic digital transmission system and WDM(wavelength division multiplex) to observation building, The wideband digital FIR(Finite Impulse Response) filters analyze the data for user observation mode to record the data in high-speed recorder with 1 Gbps. In this paper, we introduce the overall system configuration and features combined by various information and communication technology in radio astronomy briefly, which will be adopted by KVN(Korean VLBI Network).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.141-144
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• 2003

This study proposes ZnO thin film as a piezoelectric material for SAW (surface acoustic wave) filter. The ZnO thin film with thickness $2.6{\mu}m$ was deposited (0001)-oriented sapphire by RF magnetron sputtering technique. IDTs (inter-digital transducers) electrodes were patterned upon SAW filter mask with solid finger structure unapodized using lift-off method on ZnO piezoelectric thin film. SAW propagation velocity was measured with the center frequency by HP 8753C network analyzer. A fabricated ZnO SAW filter exhibited a high propagation velocity of 5433 $^m/s$ and relatively insertion loss of -53.391dB at $\lambda=80{\mu}m$. The side-lobe attenuation of the center frequency was about 17dB. When the wavelength was $80{\mu}m$ $(\lambda/4=20{\mu}m)$, the center frequency was 67.907 MHz. $k^2$ (electromechanical coupling coefficient) was 15.84 %.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.10
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• pp.909-916
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• 2016

The beacon receiver is an equipment which detects and measures the signal strength of transmitting satellite beacon signal. Beacon signals transmitted by satellites are low power continuous wave(CW) signals without any modulation intended for antenna steering to satellite direction and power control purposes on the earth. The beacon signal detection method using a very narrow band analog filter and RSSI(Received Signal Strength Intensity) has been typically used. However, it requires the implementation to track the frequency at the beacon receiver, thus a beacon frequency variation of the satellite due to temperature changes and long-term operation. Therefore, in this paper, the beacon signal detection receiver is designed by using a very narrow band digital filter array for a faster acquisition and SNR(Signal to Noise Ratio) method detection. For this purpose, by calculating the satellite link budget with the rain attenuation between satellite and ground station, and then extracting the received $C/N_o$ of the beacon signal, this work derives the bandwidth and the array number of the configured digital filter that gives the required C/N.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.8
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• pp.20-30
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• 1994

The lossless bounded real(LBR) two-pair cascade structure is one of the exiting low-sensitivity digital filter structures such as wave digital filters(WDFs) orthogonal filters. They are known to have the same structures which are composed of canonic building blocks interconnected to each other. The LBR two-pair cascade filters amount to describing in a unified manner the existing canonic low-sensitivity filters in terms of transfer matrices and chain matrices. However the existing structures have somewhat degraded low-sensitivity performance because they include dependent parameters within their structures. In this paper we propose a filter structure called “two-type-interlaced(TTI) structure.” eliminating such problem completely. This structures can be viewed as the WDFs of analog ladder circuits. As ladder circuits are obtained by cascading Brune sections and merging neighboring inductors or capacitors. so TTI structures at e obtained by cascading Type 3 LBR two-pairs and merging neighboring Type 1 LBR two-pairs. Next, a test procedure called “LBR test” is also presented in this paper. which determines whether of not the quantized TTI structure is stable . If it is unstable we can fine-tune the quantized parameters to make the overall structure stable. Therefore we can solve the dependent parameter problem completely with TTI structure along with LBR test. test.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.4
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• pp.74-82
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• 1992

This paper deals with the scheduling problems, which are the most important subtask in High-level Synthesis. ILP(integer linear programming) formulations are used as a scheduling problem approach.For practical application to digital system design, we have concentrated our attentions on pipelined datapath scheduling. For experiment results, we choose the 5-th order digital wave filter as a benchmark and do the schedule. Finally, we can obtain better and near-optimal scheduling results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.03b
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• pp.25-25
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• 2010

This paper describes the design and fabrication of a Risk Voltage Meter (RVM) which can analyze the step and touch voltages in grounding systems. The meter consists of a sine-wave power source which generates up to 300 [$V_{rms}$] in ranges of 45 [Hz]~1 [kHz], a 8 Ch. data acquisition module, and a personal computer. Also, a noise elimination method by a digital band-pass filter during measurement is proposed.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.3-7
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• 2001

In active sonar system using CW signal, when the noise included reverberation has not the white characteristics, the CFAR detector estimates high threshold. Because of this reason it cannot detect targets and not resolve the closely spaced multiple targets. In order to solve these problems, we propose an adaptive reverberation rejection filter The proposed filter is composed of an adaptive filter and a fixed filter with its coefficients. To study the performance of the proposed adaptive reverberation rejection filter, various experiments have been performed under In moving active sonar environments. As a results, the proposed method has the improved performance than the previous methods.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.7
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• pp.296-303
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• 1986

The active filter of current injection type is the device which eliminates the harmonics in ac line by injecting the harmonic compensating current into the ac side. And its harmonic reduction performance is entirely dependent on the control scheme of the current-fed inverter and the harmonic compensating current becomes the PWM wave by the inverter. This PWM compensating current can be determined by selecting the switching function properly which eliminates the harmonics up to any order with using no independent sources. The new injection current model is derived by the proposed method which is called the optimized injection method. The overall characteristics of the proposed method are investigated through digital computation and the feasibility is proved with experimental results obtained from the Z-80 microcomputer control of the active filter.