fft 中文意思是什麼

fft 解釋
地層流體測試
  1. Optimum beamforming algorithm for pre - fft ofdm adaptive antenna array

    自適應天線陣的最佳波束成形演算法
  2. Based on the analysis of the beat frequency signal, the expression of the beat frequency phase is deduced. the expression indicates physics meanings of quantities to be detected and supplies theoretical bases for detection methods. by using two - dimensional fft, the range and velocity information of target is got out from the echo. according to the periodicity range ambiguity of symmetrical pulses in fmpcw, the processing method of sliding time window is used

    通過對差頻信號進行的分析，得出了差頻相位的具體表達式，表現出了要檢測的各量的物理意義，對檢測的方法提供了理論依據。利用二維fft方法，可以有效地提取回波中目標的距離與速度信息。對于fmpcw信號由於均勻脈沖產生的周期性距離模糊的問題，採取時間波門的處理方法。
  3. This thesis studies the law of affecting de - noise result and the selection of the threshold and the wavelet function, the combination of wavelet and fft in the fault diagnosis of turbine - generator sets : by the de - noise anslysis of blocks and sin signals, concludes : to blocks signals, usually adopts soft threshold ; the law of affecting de - noise result is when use wavelet auto - de - noise, with the increasing of decomposed level, the de - noise result becomes worse while the level blow the 3, when the level above 3 and when uses wavelet packet, it is the other way round ; the best de - noise methods of the signal is that uses " dbl " wavelet function, three level, soft and " rigrsure " threshold

    本文研究了分解層數對消噪結果影響的規律和閾值、小波函數的選取，結合小波分析與fft分析診斷汽輪發電機組的故障。通過對brocks和sin兩信號的分析，得出：對blocks信號進行分析一般採用軟閾值；分解層數對消噪結果影響的規律為用小波自動降噪在分解層數小於3時，隨著分解層數的增加，消噪結果變好，反之，則變差，用小波包降噪時隨著分解層數的增加，消噪效果變好；適宜選用dbl小波軟rigrsure閾值自動消噪。
  4. It can realizes historical data repeat, time field analysis, spectrum analysis, time delay field analysis, axis orbit analysis, digital filter, corelation analysis, holographic spectrum analysis, demodulation analysis, fft delicate analysis and so on

    能實現歷史數據回放分析、時域分析、頻域分析、時延域分析、軸心軌跡分析、數字濾波、相關分析、全息譜分析、解調分析及fft細化分析等功能。
  5. The vlf / hf by using ar presents trend of increasing, this is tallied with clinic. analyzing 5 minute hrv ( decubitus ) for 4 myocardial ifchemia sickness by using ar and fft

    現代譜估計所得的vlf / hf比值隨年齡（ 20歲）增加基本呈現增加的趨勢，與臨床認識吻合。
  6. Monitor apparatus can measure valid value of three phase voltage and current, power factor, three phase disequilibrium, instant flecker of short time and harmonic without twenty, degree and harmonic distortion total. the paper are laid on the following. ( 1 ) master plan and function of circuit, ( 2 ) hardware design including circuit and principle of a / d conversion, phase lock, liquid crystal display and keystroke and so on, ( 3 ) design of system software including digital filtering, fft, a / d conversion and monitor interface of pc, ( 4 ) system test

    監測儀能夠完成包括三相電壓、三相電流的有效值、功率因數、三相不平衡、電壓短期閃變、以及20次內的諧波、諧波相位、諧波失真總量等的測量。論文重點介紹了以下幾部分： （ 1 ）電路的總體設計和功能； （ 2 ）硬體設計，包括a d轉換、鎖相環、液晶顯示和按鍵輸入等原理和電路。 （ 3 ）系統軟體設計，包括a d轉換、 fft 、數字濾波等程序的原理和演算法以及上位機監控界面的設計； （ 4 ）系統測試。
  7. By using knife edge as object, and cmos sensor as device for image analyzing, we get edge spread function from the image and use differential operation and fft to obtain modulation transfer function of the lens, then its image quality is known

    以刀口作為目標物，以cmos作為圖像分析器件，從圖像中獲取刀口函數，經微分和fft運算，得到成像鏡頭的mtf （調制傳遞函數） ，從而得知其成像品質。
  8. The assembly language program collects and processes the data real time. comparing kinds of method of filter and arithmetic of fft, the author select the fir filter to realize pretreatment of signal and radix - 2 fft to distill the characters of librations

    通過對各種濾波方法和fft演算法進行比較，本套數據檢測和校準處理系統採用fir濾波對採集到的信號進行預處理，利用基2fft演算法來提取信號的頻率特徵。
  9. The specific research methods are listed : 1. matched filter taking the max ouput snr as the best rule correlates nonstop divided signal and divided echo to detect low snr target signal. then all one dimension divided correlation outs and done fft in portrait to leach interferential signal such as static or low rate mussy meaves, many pathway echo and so on and to take target ' s time difference and doppler frequency that combine parameters that target ' s direction taken from antenna and so on to implement target ' s orientation and tracking

    具體研究方法如下： 1 、採用以輸出信噪比最大為準則的最佳匹配濾波器來對分段的參考和目標信號作相關處理來檢測低信噪比目標信號，然後對一維分段相關輸出組作縱向傅立葉變換來濾除靜態或低速的雜波、多徑回波等干擾信號，並提取目標的時差和多普勒頻率，再結合由天線獲得的目標方向等參數，就可以實現目標的定位和跟蹤。
  10. The subregion with pure dielectric layers is analyzed by mol and the fast fourier transform ( fft ) is introduced to reduce the computing time, while the subregion with conductors is analyzed by fdfd to take advantage fully the superiorities of these two methods

    通過在純介質區域使用直線法，導體所在區域使用有限差分法分別進行求解，充分發揮兩種方法各自的優越性。由於在純介質區域中使用了直線法求解，因此該演算法具有計算時間與介質層厚度無關的突出優越性。
  11. Research of hardware implementation in fft ratl - time signal processor

    實時信號處理器的硬體實現研究
  12. It is infered signal length is short, the spectrum resolving power is low by using fft method, so the vlf % and lf % by using 2 method has great difference

    推測由於5分鐘hrv信號點數較少， fft分析時解析度不高，因此兩種方法所得極低頻vlf和低頻lf有較大差異。
  13. First, employing ordinary butterfly operations formula in fft, lifting matrixes has been got and fft transform that maps plural integer to plural integer has been achieved

    首先，通過fft中的一般蝶形運算公式，構造提升矩陣，實現fft的復整數到復整數的變換。
  14. This algorithm is based on the 16 - fft about square root decomposition, and using the phase revolution unit replaces multiplication, and uses the serial butterfly operation unit. at last, gives the correspond realization measure in fpga

    本文根據一種基於平方根分解的16點fft演算法，採用相位旋轉因子取代乘法器，並利用串列流水蝴蝶運算單元給出了一種新的實現演算法，並介紹了其在fpga中相應的實現方法。
  15. Then, according to characteristic of four kinds of butterfly operation in real number signal integer fft transform keeping modulus conjugating with symmetry, different lifting matrixes has been got and real number signal integer fft transform keeping modulus conjugating with symmetry can been achieved

    然後，根據實信號保持共軛對稱性的fft整數變換中的四類蝶形運算特點分別構造不同的提升矩陣，從而實現實信號保持共軛對稱性的fft整數變換。
  16. To utilize the advantages of dsp chips, the system should be computing sources economical. according to digital signal processing theory, the poly - phase fir can help reduce the workloads of the ddc / duc. therefore, adding the complex carrier mixers, the channelization system ( a method of using a single wideband facility to transmit many relatively narrow - bandwidth signals. by subdividing the frequency spectrum used in the wideband channel ) can be formed utilizing the characters of fft

    為了使開發出的軟體可以適用於高速dsp器件開發，節省系統資源，課題首先從數字信號處理的理論進行分析，得出可以利用抽樣率轉換的數字濾波器的特點，即多相濾波實現數字上下變頻計算負擔的減小，之後進一步將多相濾波器與頻譜搬移部分結合，通過公式的推導，得出可利用快速傅立葉變換的特點實現多路信號的通道化發射和接收的處理模型。
  17. After establishing the model of intermediate frequency direct sequence spreading spectrum ( if dsss ) receiver, comparing and analyzing several conventional code acquisition methods, code and carrier two - dimension fast acquisition scheme based on two - dimension fft is proposed. finally, the situation for two targets is analyzed

    首先在建立了中頻直擴接收機的模型之後，本文對常用的偽碼捕獲方法進行了詳細地分析和比較，然後提出了本文的基於二維傅立葉變換技術的快速捕獲方法，並且分析了兩個目標時的情況。
  18. 2. design the pulse compression program of one piece of adsp - ts203. complete the program and optimization of radix - 2 fft independently, which meets real - time processing

    2 .基於一片ts203的脈沖壓縮處理單元的程序設計，獨立完成其中基2 - fft的編寫及其優化，滿足系統實時性的要求。
  19. From the result we get the following conclusion : for narrow - band signal, the effect of the method based on fft is best. for wide - band signal, when snr is up to certain degree ( higher than - 7db or so ), the curves of square error of modified methods are more obvious and closer to crb. for an echo composed of more than one frequency or direction, space - frequency distribution could show more direct information of frequency and direction, which is more advantaged to make precise judge and estimation for doa of echo

    從估計結果發現，對于窄帶回波信號，基於fft的方法估計性能大大優于其他方法；對于寬帶回波信號，在信噪比達到一定程度（高於約- 7db ）時，補償后的幾種估計法的性能改善均比較明顯，誤差曲線越來越接近crb曲線；對于回波中存在多頻率多方位的情況，空間?頻率分布圖能提供較為直觀的頻率及方位信息，因此應用空間?頻率估計法來進行方位估計，更有利於進一步對回波的具體方位進行準確判斷和估計。
  20. The signal process function of the software include these function : digital filter, windowing, auto - correlation function and cross - correlation function, mean and variance, probability density function and probability distribution function statistic ; auto - power spectrum, cross - power spectrum, frequency response function, coherence function, cepstrum analysis based on fft ( fast fourier transfer ) ; joint time - frequency analysis based on stft ( short - time fourier transfer )

    軟體的處理功能包括：數字濾波、時域加窗、自相關與互相關處理、均值和方差計算、概率密度和概率分佈函數計算；在快速傅立葉變換（ fft ）基礎上計算自功率譜、互功率譜、頻率響應函數、相干函數、倒頻譜分析；基於短時傅立葉變換（ stft ）的聯合時頻分析等。
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