• 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 KSME Conference
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• 2003.11a
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• pp.1654-1659
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• 2003

This paper introduces a fast Fourier transform (FFT)-based spectral analysis method for the transient responses as well as the steady-state responses of linear discrete systems. The force vibration of a viscously damped three-DOF system is considered as the illustrative numerical example. The proposed spectral analysis method is evaluated by comparing with the exact analytical solutions as well as with the numerical solutions obtained by the Runge-Kutta method.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.14 no.1
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• pp.49-58
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• 1996

This paper deals with the gravimetric solution of geoid by Fast Fourier Transform(FFT) technique in and around Korean Peninsula. The used reference surface is OSU91A geopotential model up to degree and order 180 refered to GRS80. The remove and restore technique was applied to obtain the geoidal height in this paper. And the FFT with 20% window was applied to compute the medium wavelength effect from terrestrial gravity anomalies. For the comparison of computed results, the geometric geoidal height was derived from GPS/Levelling data. According to the comparison, the mean value and RMSE of the differences are 0.3819m and 0.4695m respectively.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.169-174
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• 2015

In this study, we developed a system to detect the various defects in the metallic objects using the phenomenon that the defects cause the changes of the natural resonant frequencies. Our system consists of a FFT Amp, an Auto Impact Hammer, a Hammer controller and a PC. Auto Impact Hammer creates vibrations in the metallic objects when tapped on the surface. These vibrational signals are converted to the voltage signals by an acceleration sensor attached to the metallic part surface. These analog voltage signals were fed into an ADC (analog-digital converter) and an FFT (fast fourier transform) conversion in the FFT Amp to obtain the digital data in the frequency domain. Labview graphical program was used to process the digital data from th FFT amp to display the spectrum. We compared those spectra with the standard spectrum to find the shifts in the resonant frequencies of the metal parts, and thus detecting the defects. We used PCB's acceleration sensor and TI's TMS320F28335 DSP (digital signal processor) to obtain the resolution of 2.93 Hz and to analyze the frequencies up to 44 kHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.10
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• pp.36-42
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• 2010

FFT(Fast Fourier Transform) processor is one of the key components in the implementation of OFDM systems for many wireless standards such as IEEE 802.22. To improve the performances of FFT processors, various studies have been carried out to reduce the complexities of multipliers, memory interface, control schemes and so on. While the number of FFT stages increases logarithmically $log_2N$) as the FFT point-size (N) increases, the number of required registers (or, memories) increases linearly. In large point-size FFT designs, the registers occupy more than 70% of the chip area. In this paper, to reduce the memory size of IFFT for OFDM transmitters, we propose a new IFFT design method based on a combined mapping of modulated data, pilot and null signals. The proposed method focuses on reducing the sizes of the registers in the first two stages of the IFFT architectures since the first two stages require 75% of the total registers. By simulations of 2048-point IFFT design for cognitive radio systems, it is shown that the proposed IFFT design method achieves more than 38.5% area reduction compared with previous IFFT designs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.499-503
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• 2000

The use of Multiple-Valued FFT(Fast fourier Transform) is extended from binary to multiple-valued logic(MVL) circuits. A multiple-valued FFT circuit can be implemented using current-mode CMOS techniques, reducing the transitor, wires count between devices to half compared to that of a binary implementation. For adder processing in FFT, We give the number representation using such redundant digit sets are called redundant positive-digit number representation and a Redundant set uses the carry-propagation-free addition method. As the designed Multiple-valued FFT internally using PD(positive digit) adder with the digit set 0,1,2,3 has attractive features on speed, regularity of the structure and reduced complexities of active elements and interconnections. for the mutiplier processing, we give Multiple-valued LUT(Look up table)to facilitate simple mathmatical operations on the stored digits. Finally, Multiple-valued 8point FFT operation is used as an example in this paper to illuatrates how a multiple-valued FFT can be beneficial.

• Journal of the Korea Computer Industry Society
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• v.3 no.1
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• pp.57-66
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• 2002

In this study, Multi-Values Logic processor was designed using the basic circuit of the electric current mode CMOS. First of all, binary FFT(Fast Fourier Transform) was extended and high-speed Multi-Valued Logic processor was constructed using a multi-valued logic circuit. Compared with the existing two-valued FFT, the FFT operation can reduce the number of transistors significantly and show the simplicity of the circuit. Moreover, for the construction of amount was used inside the FFT circuit with the set of redundant numbers like ［0,1,2,3］. As a result, the defects in lines were reduced and it turned out to be effective in the aspect of normality an regularity when it was used designing VLSI(Very Large Scale Integration). To multiply FFT, the time and size of the operation was used as LUT(Look Up Table) Finally, for the compatibility with the binary system, multiple-valued hybrid-type FFT processor was proposed and designed using binary-four valued encoder, four-binary valued decoder, and the electric current mode CMOS circuit.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.4
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• pp.504-511
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• 2012

In this paper, level instrument is implemented using beat frequency for distance measurement which means the difference between Tx and Rx signal frequency from FMCW Radar Level Transmitter. Beat frequency is analyzed through Fast Fourier Transform of which frequency precision can be improved by applying Zoom FFT. Distance precision is improved from 146.5[mm] to 5[mm] using the advantage of Zoom FFT which can raise the frequency precision without changing the sampling frequency or FFT point number to be fixed in the beginning of designing signal processing. Also, measurement error can be reduced within 2[mm] by incresing the FFT points using the method of Spline interpolation. For verifying the effectiveness of this Zoom FFT to FMCW Radar Level Transmitter, test bench is made to measure the distance for every 1[mm] between 700[mm] and 2000[mm] and measurement error can be checked in the range of ${\pm}2$[mm].

• Journal of the Korean Magnetics Society
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• v.6 no.3
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• pp.174-178
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• 1996

A method was studied which simulate signal and noise for magneto-optical disk drive system Recorded mark patterns and incident laser beam were modeled and discretized. Using them readout waveformj and amplitude were simulated. Adding Gaussian random noise to the readout signal and executing one dimensional discrete FFT (Fast Fourier Transform) algorithm signal and noise spectrum was estimated. From the spectrum, CNR (Carrier to Noise Ratio) was obtained.

• Journal of Magnetics
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• v.19 no.1
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• pp.90-100
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• 2014

Position estimation that uses only active phase voltage and current is presented, to perform high accuracy position sensorless control of a SRM drive. By extracting the amplitude of the first switching harmonic terms of phase voltage and current for a PWM period through Fast Fourier Transform (FFT), the flux-linkage and position are estimated without external hardware circuitry, such as a modulator and demodulator, which result in increased cost, as well as large position estimation error, produced when the motional back EMF is ignored near zero speed. A two-phase SRM drive system, consisting of an asymmetrical converter and a conventional closed-loop PI current controller, is utilized to validate the performance of the proposed position estimation scheme in comprehensive operating conditions. It is shown that the estimated values very closely track the actual values, in dynamic simulations and experiments.