• Management & Information Systems Review
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• v.3
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• pp.201-214
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• 1999

Adaptive correlator receiver with neural network based on complex multilayer perceptron is persented for suppressing interference of narrow-band of direct spread spectrum communication systems. Recursive least square algorithm with backpropagation error is used for fast convergence and better performance in adaptive correlator scheme. According to signal noise and transmission power, computer simulation results show that bit error ratio of adaptive correlator using neural network improved that of adative transversal filter of direct sequence spread spectrum considering of jamming and narrow-band interference. Bit error ratio of adaptive correlator with neural network is reduced about 10-1 than that of adaptive transversal filter where interference versus signal ratio is 5dB.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.173-176
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• 1999

Frequency responses of the surface acoustic wave(SAW) filters are simulated by using the impulse modeling. The simulation technique of the SAW filters is to use the Fourier transformation to make a correspondence between the impulse response of the filter and the taps in the delay line. Since the Fourier series must be truncated after a finite number of terms, window functions are often used to weight the coefficients to obtain the desirable side-lobe level and bandwidth. The filter design is operated through the iterative simulation procedures. The design process is capable of yielding filters with optimized frequency response characteristics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.5
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• pp.36-41
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• 2007

We report the 94 GHz CPW branch-line bandpass filter for planar integrated millimeter-wave circuits. The branch-line coupler operates as a transversal filtering section by connecting the coupling ports to the open load stubs and taking the isolation port as the output node. For design of the 94 GHz branch-line bandpass filter, we built the CPW library and optimized the characteristic impedances and the lengths of the branch-line coupler and the open load stubs. The fabricated 94 GHz bandpass filter exhibits an insertion loss of 2.5 dB with an 11.7 % 3 dB relative bandwidth and the return loss is -18.5 dB at a center frequency of 94 GHz.

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.70-72
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• 1984

본 논문에서는 음성신호에 섞인 잡음을 효과적으로 제거하기 위해 Two-sided Transversal Filter를 이용하는 방법을 제시하였다. 이 방법은 기존의 방법과는 달리 신호의 단기자기상관관계(short-term autocorrelation)을 충분히 이용하기 위해 적응 필터의 입력으로, 지연된 신호뿐만 아니라 미래의 신호도 이용하도록 하였다. 이 결과 음성신호에 섞인 잡음(백색잡음, 유색잡음)을 아주 효과적으로 제거함을 알 수 있다.

• Speech Sciences
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• v.11 no.2
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• pp.227-235
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• 2004

In this paper, we proposed a new practical implementation method of the lattice transversal joint (LTJ) adaptive filter using speech codec's information. And it was applied to the adaptive echo cancellation problem to verify the efficiency of the proposed method. Realtime implementation of the LTJ adaptive filter is very difficult due to high computational complexity for the filter coefficients compensation. However, in case of using speech codec, complexity can be reduced since linear predictive coding (LPC) coefficients are updated each frame or sub-frame instead of every sample. Furthermore, LPC coefficients can be acquired from speech decoder and transformed to the reflection coefficients. Therefore, the computational complexity for updates of the reflection coefficients can be reduced. The effectiveness of the proposed LTJ adaptive filter was verified by the experiments about convergence and tracking performance of the adaptive echo canceller.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.6
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• pp.881-888
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• 1993

A new stabilizing algorithm for the fast transversal filter (FTF) which is known to exhibit a very unstable behavior, due basically to the accumulation in two different ways, we define a emasure counting these at each step of the algorithm in order to reduce the roundoff error. It has been shown that required amount of computation for the proposed algorithm is linearly increased as the order of equalizer and that stability is improved in comparison with the other existing algorithm. It has been shown that the proposed algorithm exhibits a good performance using computer simulation of adaptive equalization for multipath fading channel in urban mobile radio environment.

• Journal of Biomedical Engineering Research
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• v.15 no.4
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• pp.395-400
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• 1994

High resolution spectral analysis is essential for ECG anaysis. The fast Fourier transform has been widely used for frequency analysis of ECG signals but this procedure provides poor resolution when the data record is short and shows Gibb's phenomena. The ARMA FTF (Fast Transversal Filter) algorithm is used for high resolution spectral analysis. The reason of unsalability of this algorithm is investigated and the method for improving the numerical stability is proposed. The proposed algorithm is applied to spectral analysis of the ECG. Since this result has less variations than the FFT based results, it can be used for the computerized diagonosis of the ECG.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.56-59
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• 1997

SAW filters of transversal type were fabricated on some piezoelectric substrates of the LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$Y-X, Quartz ST-cut wafers through the simulation in which the number o: IDT and window function were changed for the required frequency, and the mask making. Their IDT spacing and width were 3 ${\mu}{\textrm}{m}$, chip size was 4.462 $\times$ 2.086 mm$^2$, and they had double electrode transversal type IDTs. In addition to pure Al electrode devices, Ti thin films having the different thicknesses was introduced between the Al electrode and the substrate for improving the power resistance strength. They had 11-12 dB insertion losses similar to those of pure Al electrode SAW filters in case of LN 128$^{\circ}$ Y-X, LN 64$^{\circ}$ Y-X, meaning that Ti thin film was not detrimental to the insertion loss and general frequency properties. The filters had the center frequencies 162MHz for LN 128$^{\circ}$ Y-X, 186MHz for 64$^{\circ}$ Y-X, and 131MHz for Quartz ST-cut substrates.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.45-48
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• 2001

In this paper, the characteristic of the equalizer using Lattice filter was investigated in channel ISI (Inter-Symbol Interference) in OFDM (orthogonal frequency division multiplexing) system. The equalizer using lattice filter has more fast convergence and little equalization error characteristic in two number of tap by orthogonal effect of each tap than another equalizers. The filter coefficient convergency and static BER (bit error ratio) characteristic was analysed by computer simulation. In this paper, it is shown that the equalizer using lattice filter has the better performance than a equalizer which makes use of another equalization method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.1008-1014
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• 2002

This paper is concerned about multiplierless interpolation FIR filters. In this paper, we propose a filter that performs T tap 1:N interpolation FIR filter operation with B-bit inputs without using multipliers. This is done by applying a method which converts a 2s complement multi-bits input to multiple single-bit inputs and a lookup table minimization method which reduces the size of lookup tables by use of the symmetry of filter coefficients and the symmetry of each lookup table. Two FIR filters are implemented using the methods proposed in this paper. Each of the two filters respectively follows the two design parameters in the specification of IMT-2000. Those two FIR filters have an advantage that the number of required gates is reduced up to 70% comparing to that of a conventional transversal FIR filter.