In this paper , we firstly design orientation filters based on directional image of fingerprint and employ them to denoise gray - scale image . then , we binarize the gray - scale image with local self - adaptive binarization smoothness algorithm and eliminate the noises from the binary image with fast fourier transform algorithm 本文先基于指纹的方向图设计出方向滤波器对原图像进行滤波去噪，然后使用局部平滑阈值自适应二值化算法，将灰度图像进行二值化，并采用快速傅氏变换对所得到的二值化图像进行去噪处理。
It involves not only the detection of signal frequency , signal phase and power factor but also calculation and control of phase . the method of calculating phase is based on fast fourier transform algorithm ( fft ) . it is used to calculate signal frequency , signal phase , power factor and the phase on / off time according to sampling instantaneous value of voltage and current 本文主要提出了采用信号处理技术(快速傅里叶变换fft ) ，根据电压、电流采样的瞬时值，计算信号频率、信号相位、功率因数、分合闸相角的选相控制方法，并介绍了最终控制分合闸的原理与实现方法
The digitizer based on pxi bus uses fpga ( field programmable gate array ) to implement 256 points , radix - 2 dit fft ( fast fourier transform algorithm ) . the design uses pipelining for fft processing and can accomplish sampling and processing signals of two channels at the same time . in the signal acquisition circuit , - a / d convector is used to enhance the precision of the signal sampling 在本设计中,采用fpga ( fieldprogrammablegatearray )实现了256点基2dit算法复数fft ( fastfouriertransformalgorithm快速傅氏变换算法)处理器,具有较高的速度和运算精度fft ,设计采用流水线处理方式大大的提高了处理速度,可实现对两个通道输入信号的并行采集与处理。
