• Title, Summary, Keyword: fast fourier transform

Search Result 768, Processing Time 0.042 seconds

Study of Radix-3 FFT (Radix-3 FFT에 관한 고찰)

  • Jung, Hae-Seung
    • Aerospace Engineering and Technology
    • /
    • v.9 no.1
    • /
    • pp.98-105
    • /
    • 2010
  • Fast Fourier Transform is the fast implementation of Discrete Fourier Transform, which deletes periodic operation of DFT. According to the definition, radix-2 FFT can be implemented byre cursive call which divides the input signal points into 2 signal points. Because of its time-consuming stack-copy operation, this recursive method is very slow. To overcome this drawback, butterfly operation with signal rearrangement was devised. Based on the ideas of signal rearrangement and butterfly operation, this paper applies the signal rearrangement method to the Radix-3 FFT and checks the validity of this method.

Effect of Synchronization Errors on the Performance of Multicarrier CDMA Systems

  • Li Ying;Gui Xiang
    • Journal of Communications and Networks
    • /
    • v.8 no.1
    • /
    • pp.38-48
    • /
    • 2006
  • A synchronous multicarrier (MC) code-division multiple access (CDMA) system using inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) for the downlink mobile communication system operating in a frequency selective Rayleigh fading channel is analyzed. Both carrier frequency offset and timing offset are considered in the analysis. Bit error rate performance of the system with both equal gain combining and maximum ratio combining are obtained. The performance is compared to that of the conventional system using correlation receiver. It is shown that when subcarrier number is large, the system using IFFT/FFT has nearly the same performance as the conventional one, while when the sub carrier number is small, the system using IFFT/FFT will suffer slightly worse performance in the presence of carrier frequency offset.

N-Point Fast Fourier Transform Using 4$\times$4 Fast Reverse Jacket Transform (4-점 리버스 자켓 변환를 이용한 N-점 고속 푸리에 변환)

  • 이승래;성굉모
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.26 no.4B
    • /
    • pp.418-422
    • /
    • 2001
  • 4-점 리버스 자켓 변환 (4-Point Reverse Jacket transform)의 장점 중의 하나는 4-점 fast Fourier transform(FFT)시 야기되는 실수 또는 복소수 곱셈을 행렬분해(matrix decomposition)를 이용, 곱셈인자를 모두 대각행렬에만 집중시킨, 매우 간결하고 효율적인 알고리즘이라는 점이다. 본 논문에서는 이를 N 점 FFT에 적용하는 알고리즘을 제안한다. 이 방법은 기존의 다른 변환형태보다 확장하거나 구조를 파악하기에 매우 용이하다.

  • PDF

A Pipelined Hadamard Transform Processor (파이프라인 방식에 의한 아다마르 변환 프로세서)

  • 황영수;윤대희;차일환
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.26 no.10
    • /
    • pp.1617-1623
    • /
    • 1989
  • The introduction of the fast Fourier transform(FFT),an efficient computational algorithm for the discrete Fourier transform(DFT) by Cooley and Tukey(1965), has brought to the limelight various other discrete transforms. Some of the analog functions from which these transforms have been derived date back to the early 1920's, for example, Walsh functions (Walsh, 1923) and Hadamard Transform(Enomoto et al, 1965). Fast algorithms developed for the forward transform are equally applicable, exept for minor changes, to the inverse transform. In this paper, we present a simple pipelined Hadamard matrix(HM) which is used to develop a fast algorithm for the Hadamard Processor (HP). The Fast Hadamard Transform(FHT) can be derived using matrix partitioning techniques. The HP system is incorporated through a modular design which permits tailoring to meet a wide range of video data link applications. Emphasis has been placed on a low cost, a low power design suitable for airbone system and video codec.

  • PDF

A Comparison between Abel-Fourier and Digital Linear Filter Methods (Abel-Fourier법과 디지탈 선형필터법과의 비교)

  • Kim, Hee Joon
    • Economic and Environmental Geology
    • /
    • v.20 no.2
    • /
    • pp.119-123
    • /
    • 1987
  • Hankel transform of order 0 can be represented by a combination of Abel transform and Fourier transform. This Abel-Fourier method can offer computational advantages over a conventional digital linear filter method through the uses of a rapid Abel transform with shift variant recursive filter and of a fast Fourier transform. The Abel-Fourier method, however, is generally less accurate than a well-designed digital linear filter method. In geoelectrical applications, the digital linear filter method seems to be more flexible than the Abel-Fourier method.

  • PDF

Modification of the fast fourier transform-based method by signal mirroring for accuracy quantification of thermal-hydraulic system code

  • Ha, Tae Wook;Jeong, Jae Jun;Choi, Ki Yong
    • Nuclear Engineering and Technology
    • /
    • v.49 no.5
    • /
    • pp.1100-1108
    • /
    • 2017
  • A thermal-hydraulic system code is an essential tool for the design and safety analysis of a nuclear power plant, and its accuracy quantification is very important for the code assessment and applications. The fast Fourier transform-based method (FFTBM) by signal mirroring (FFTBM-SM) has been used to quantify the accuracy of a system code by using a comparison of the experimental data and the calculated results. The method is an improved version of the FFTBM, and it is known that the FFTBM-SM judges the code accuracy in a more consistent and unbiased way. However, in some applications, unrealistic results have been obtained. In this study, it was found that accuracy quantification by FFTBM-SM is dependent on the frequency spectrum of the fast Fourier transform of experimental and error signals. The primary objective of this study is to reduce the frequency dependency of FFTBM-SM evaluation. For this, it was proposed to reduce the cut off frequency, which was introduced to cut off spurious contributions, in FFTBM-SM. A method to determine an appropriate cut off frequency was also proposed. The FFTBM-SM with the modified cut off frequency showed a significant improvement of the accuracy quantification.

Efficient IFFT Design Using Mapping Method (Mapping 기법을 이용한 효율적인 IFFT 설계)

  • Jang, In-Gul;Kim, Yong-Eun;Chung, Jin-Gyun
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.44 no.11
    • /
    • pp.11-18
    • /
    • 2007
  • FFT(Fast Fourier Transform) processor is one of the key components in the implementation of OFDM systems such as WiBro, DAB and UWB systems. Most of the researches on the implementation of FFT processors have focused on reducing the complexities of multipliers, memory and control circuits. In this paper, to reduce the memory size required for IFFT(Inverse Fast Fourier Transform), we propose a new IFFT design method based on a mapping method. By simulations, it is shown that the reposed IFFT design method achieves more than 60% area reduction and much SQNR(Signal-to-Quantization-Noise Ratio) gain compared with previous IFFT circuits.

Effects and Limitations of Separating Overlapped Fingerprints Using Fast Fourier Transform (고속 푸리에 변환(fast Fourier transform, FFT)을 이용한 겹친지문 분리의 효과와 한계)

  • Kim, Chaewon;Kim, Chaelin;Lee, Hanna;Yu, Jeseol;Jang, Yunsik
    • Korean Security Journal
    • /
    • no.61
    • /
    • pp.377-400
    • /
    • 2019
  • Photography is the most commonly used method of documenting the crime and incident scene as it helps maintaining chain of custody (COC) and prove integrity of the physical evidence. It can also capture phenomena as they are. However, digital images can be manipulated and lose their authenticity as admissible evidence. Thus only limited techniques can be used to enhance images, and one of them is Fourier transform. Fourier transform refers to transformation of images into frequency signals. Fast Fourier transform (FFT) is used in this study. In this experiment, we overlapped fingerprints with graph paper or other fingerprints and separated the fingerprints. Then we evaluated and compared quality of the separated fingerprints to the original fingerprints, and examined whether the two fingerprints can be identified as same fingerprints. In the case of the fingerprints on graph paper and general pattern-overlapping fingerprints, fingerprint ridges are enhanced. On the other hand, in case of separating complicated fingerprints such as core-to-core overlapping and delta-to-delta overlapping fingerprints, quality of fingerprints can be deteriorated. Quality of fingerprints is known to possibly bring negative effects on the credibility of examiners. The result of this study may be applicable to other areas using digital imaging enhancement technology.

Surface Temperature in Sliding Systems Using the FFT Finite Element Analysis (FFT-FEM을 이용한 윤활 기구에서 표면온도에 관한 연구)

  • 조종두;안수익
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
    • /
    • /
    • pp.73-79
    • /
    • 1999
  • Finite element equations by using fast Fourier transformation were formulated for studying temperatures resulting from frictional heating in sliding systems. The equations include the effect of velocity of moving components. The program developed by using FFT-FEM that combines Fourier transform techniques and the finite element method, was applied to the sliding bearing system. Numerical prediction obtained by FFT-FEM was in an excellent agreement of experimental temperature measurements.

  • PDF