公开(公告)号：US06732058B2

公开(公告)日：2004-05-04

申请号：US10134382

申请日：2002-04-30

申请人： Dongxing Jin ,  Ping Wan ,  Derrick Remedios ,  Leonard Marziliano

发明人： Dongxing Jin ,  Ping Wan ,  Derrick Remedios ,  Leonard Marziliano

IPC分类号： G06F1900

CPC分类号： G06F17/142 ,  G06F17/141 ,  G06F17/147

摘要： Various methods and apparatuses are provided for performing a radix-M FFT (Fast Fourier Transform) upon N time domain samples to produce N/S frequency domain samples for detecting tones of dithers impressed on channels of a WDM (wavelength Division Multiplexed) optical signal. Successive tones have a tone frequency spacing, &Dgr;fta, and a sampling frequency, fs, is chosen so that fs=N&Dgr;fta/S. S is a spacing given by S=Mw with w being an integer. The radix-M FFT is performed in k=logm(N) stages and within the stages a reduced number of radix-M computations, when compared to the number of radix-M computations of a conventional radix-M FFT, are performed on data points associated with the N time domain samples. This is possible because successive frequency domain samples of the N/S frequency domain samples differ by &Dgr;fta=S&Dgr;f where &Dgr;f is a frequency bandwidth.

摘要翻译： 提供了各种方法和装置，用于在N个时域样本上执行基数M FFT（快速傅立叶变换），以产生N / S频域样本，用于检测印在WDM（波分复用）​​光信号的信道上的抖动的音调。 连续色调具有音频间隔Deltafta，并且选择采样频率fs，使得fs = NDeltafta / S。 S是由S = M 给出的间隔，其中w是整数。 在k = logm（N）个阶段中执行基数M FFT，并且在与数据的基数-M计算的数量相比较时，减少数量的基数M计算的阶段执行数据 与N个时域样本相关联的点。 这是可能的，因为N / S频域样本的连续频域样本随Deltafta = SDeltaf而不同，其中Deltaf是频带宽度。

公开(公告)号：US06963892B2

公开(公告)日：2005-11-08

申请号：US10025870

申请日：2001-12-26

申请人： Dongxing Jin ,  Ping Wan ,  Leonard Marziliano

发明人： Dongxing Jin ,  Ping Wan ,  Leonard Marziliano

IPC分类号： G06F17/14 ,  F06F15/00

CPC分类号： G06F17/142

摘要： A method and apparatus for performing a fast Fourier transform (FFT) computation on large data sizes in real time is provided. The speed at which a FFT is performed is increased by reducing the number of times a Direct Memory Access (DMA) unit must transfer data between an internal memory and an external memory. This is achieved through an algorithm in which data is imported from the external memory into the internal memory and having the CPU perform several calculations on the imported data before it is exported back to the external memory. The imported data in the internal memory has a structure that results in a reduction of the number of times the imported data is swapped between different layers of the internal memory during the FFT computation. Furthermore, the DMA unit import/exports data between the internal memory and the external memory while at the same time having the CPU perform calculations on other data in the internal memory.

摘要翻译： 提供了一种用于对大数据量实时执行快速傅立叶变换（FFT）计算的方法和装置。 通过减少直接存储器访问（DMA）单元必须在内部存储器和外部存储器之间传送数据的次数来增加执行FFT的速度。 这是通过将数据从外部存储器导入内部存储器并使CPU在导出到外部存储器之前对导入的数据执行多个计算的算法来实现的。 内部存储器中导入的数据具有导致FFT计算期间导入的数据在内部存储器的不同层之间交换次数的结构。 此外，DMA单元在内部存储器和外部存储器之间导入/导出数据，同时使CPU对内部存储器中的其他数据执行计算。