• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.3091-3093
• /
• 2000

FFT 알고리즘은 DC 성분에서부터 나이퀴스트 주파수까지 주파수 성분에 관한 해석이며, 주파수 정밀도는 DC 성분에서부터 나이퀴스트 주파수까지의 샘플 수에 의존했다. 하지만 많은 경우, 특정한 주파수 대역에 대한 주파수 정보를 보다 정확하게 분석하고자 하는 상황이 나타난다. 이렇게 특정 주파수 대역에 대해서 확장된 분석을 수행하는 것을 Zoom FFT라 한다. 하지만, 이러한 Zoom FFT를 수행한다 할지라도 FFT 알고리즘이 가지는 특성상 입력 신호가 가지는 정확한 주파수 성분을 얻는다는 것은 불 가능하다. 본 논문에서는 Zoom FFT를 수행하는 방법과 수행했을 때 발생하는 에러에 관해서 다룬다.

• Journal of Biomedical Engineering Research
• /
• v.24 no.3
• /
• pp.175-181
• /
• 2003

Studies of muscle fatigue have mostly been checked under isometric exercise. However EMG signals from isotonic exercise generate uncontrollable noise, so there were difficulties in gathering reliable median frequency and muscle fatigue index if frequency analysis was equally applied in isometric exercise. This study tried to compare the differences of muscle fatigue determinant variables in terms of median frequency searching methods of EMG signal, which was estimated in isotonic exercise. To accomplish this, we determined median frequency by using different FFT intervals and overlapping ration of consecutive FFT sections under the same EMG signal, and then searched for a linear regression line, and compared initial median frequency, slope, and muscle fatigue index which were variables under the linear regression line. In result of comparison, initial median frequency was more elevated as FFT exercise interval became larger. The slope of the linear regression line showed distinguishable decreasing tendency as FFT intervals were larger and overlapping sections were smaller. Significant tendency of muscle fatigue index in FFT interval was shown by high muscle fatigue index in specific FFT intervals.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.11a
• /
• pp.562-564
• /
• 1998

보통 음향 신호를 분석을 할 때에 시간영역의 신호를 주파수영역의 신호로 FFT 변환을 해서 분석을 한다. 이렇게 단순히 FFT를 해서 주파수영역의 신호에서 어떤 특징적인 점을 찾기가 매우 어렵다. 그래서 원 신호를 FFT를 하지 않고 선형 예측 분석이라는 방법을 적용하여 신호에 특징적인 피크 점들을 구하면 쉬운 방법이 된다. 본 논문에서는 이러한 음향의 신호를 분석을 할 때에 선형 예측 분석법을 이용하면 신호에서 특징적인 피크들을 구하기가 용이함을 보이고 신호의 특징 피크 점들을 통계적으로 처리하여 분석을 해보았다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.12 no.1
• /
• pp.33-37
• /
• 2011

This paper presents the frequency spectral analysis based on FFT of the infrared ray fire thermal image, it is an object to deduce the conditions for determining fire alarm through the image processing with the frequency domain. After the candidate regions are separated by using pre-defined brightness value, the fast fourier transform is performed for consecutive infrared thermal images, the frequency spectral analysis of the thermal image analyzed DC and AC frequency distribution. The fire criterion of the thermal image was presented based on the analyzed result and a practicality was confirmed through the computer simulation.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.6
• /
• pp.29-34
• /
• 2007

It is important to analyse the frequency spectrum for the measurement of modulated signal, distortion, and noise. The frequency spectrum analysis is performed by the execution of Radix-2 DIT DFT i.e. FFT algorithm. The discrete input signal converted by A/D converter from the input signal in time domain is mathematically transformed to the frequency spectrum by FFT algorithm. In this study, we design the digital spectrum analyser by the hardware based on the TMS320F2812 DSP and AD9244 converter, and by the software based on the C28x S/W modules. We can timely analyse the frequency spectrum in mobile communication system by the digital frequency analyser based on the high performance DSP and S/W modules. This real-time analysing capability is the important performance in the internet-based mobile communication server system.

• Journal of Satellite, Information and Communications
• /
• v.9 no.2
• /
• pp.38-44
• /
• 2014

This paper presents design of a FMCW (Frequency Modulated Continuous Wave) level meter as well as simulation result of the designed system. The system is designed to measure maximum range of 20m since FMCW radar can be used for measuring short range distance. The distance is measured by analyzing the beat signal which is generated as result of mixing transmitting signal with the reflected received signal. The Fast Fourier Transform is applied to analyze the beat signal for calculating the displacement and Zoom FFT technique is used to minimize measurement error as well as increase the resolution of the measurement. The resolution of the measurement of the designed system in this paper is 2.2mm and bandwidth of 1.024GHz is used for simulation. Thus the simulation results are analyzed and compared in various conditions in order to get a comprehensive idea of frequency resolution and displacement resolution.

• The Journal of the Acoustical Society of Korea
• /
• v.14 no.2
• /
• pp.30-39
• /
• 1995

In this paper, study on implementation of FFT analyzer applied to CAT, A/D conversion module, DSP module and VXIbus interface module are implemented in hardware and calculation program and control software are implemented in DSP module and VXIbus interface module, respectively. The control of the modules using PC is realized in software. The real time bandwidth of the FFT analyzing device is 100KHz. At sampling rate of 200KHz and with 2048 point FFT, the result of applying sine, triangular and rectangular wave of 20KHz to FFT analyzing device is compared with the FFT analyzed results of Hewlett-Packard 3562A dynamic output range of -40dBV- +30dBV, correct results are obtained and results of applying 10KHz, 20KHz and 50KHz input are compared and the correct values are obtained.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.293-296
• /
• 2016

Speech Signals consist of signals of consonants and vowels, but the lasting time of vowels is much longer than that of consonants. It can be assumed that the correlations between signal blocks in speech signal is very high. But the correlations between signal blocks in various frequency bands can be quite different. Each speech signal is divided into blocks which have 128 speech data. FFT is applied to each block. Various frequency areas of the results of FFT are taken and Covariance matrix between blocks in a speech signal is extracted and finally eigenvalues of those matrix are obtained. It is studied that in the eigenvalues of various frequency bands which band can be used to get more reliable result.

• Journal of Korea Multimedia Society
• /
• v.14 no.11
• /
• pp.1507-1515
• /
• 2011

As the first step in research for sound synthesis of Pyungjong, timbre was analyzed by FFT analysis. There was no significant difference in the pitch of scale between modern Pyungjong and western twelve-tone equal temperament scale. The timbre of Pyunjong chagnes over time. When striking Pyunjong, the noises to be generated across all frequencies will disappear in a short period of time, and a unique partial only is left. Then it disappear from the partial of high frequency components in order, and two partials remain at release time. At this time, the beating is occurring by the frequency of the remaining partial. Pyungjong used in this study is relatively a recently manufactured Pyungjong, and for original sound synthesis of Pyungjong, a study of ancient Pyungjong's timbre should be additionally conducted later.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.999-1001
• /
• 2015

CW Doppler radar is capable of giving the relative velocity of an object using the Doppler effect. When detecting more than an object, frequency domain analysis is needed using CW Doppler radar and FFT. Even though the number of objects and velocities can be obtained within the frequency domain, there is a disadvantage that it is difficult to assess information on approach or deviation of an object. When detecting more than an object using FFT, this study suggests an algorithm for efficiently assessing information about approach or deviation of objects within the frequency domain. The proposed algorithm divides sections into real and imaginary numbers in the frequency domain, and then determines deviation if the total sum of the amplitudes of each frequency is on the left side and approach if the total sum of the amplitudes is on the right side.