Exploiting the cyclostationarity of ofdm signals in multipath environment , we further introduce an ofdm coarse frequency error estimator and an ofdm fine synchronizer 利用接收信号的循环平稳性，结合信道响应提出了一种ofdm频偏粗估计器和一种ofdm定时偏差和频偏精估计器。
2.
The coarse frequency error estimator has a wide estimation range and may be used for initial caption . and the fine estimator can achieve nice performance in multipath environment 该粗估计器有很大的估计范围，可用于频偏的捕获；而精估计器在多径环境下能得到很好的估计效果。
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As for the design of alloy system and the determination of the quantity of main contents , they rely on the approximate estimation after simply calculation , which result in longer development cycle , higher cost and worse accuracy 在合金系统的设计和某些主要成分的用量上，辅以简单计算进行粗估，设计周期长、开发成本高。因此，焊材设计手段的更新至关重要。
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We select fpga of type xc3s200 as hardware to design the coder and display the hardware resources inside , moreover study the method and steps of designing dsp , based on fpga , by using system generator , finally , it emphasizes the design process of multi - band excitation vocoder . we can work out the module of high pass filter and the module of low pass filter , module of divide frame , module of keynote rough estimate , module of keynote fine estimate , module of band - separated v / u judgment / verdict and module of band - separated amplitude estimate , by using simulink , ise and system generator 本文选用型号为xc3s200的fpga作为设计编码器的核心硬件,介绍了其内部所含的硬件资源,并研究了利用systemgenerator基于fpga设计dsp的方法和步骤,最后,本文把重点放在多带激励语音编码器的设计上,利用simulink , ise和systemgenerator分别设计其中的高通低通滤波器模块、分帧叠加模块、基音粗估模块、基音精细估计模块、分带v / u判决模块、分带幅度估计模块。
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Firstly , it introduces the development of speech coding , along with the significance of the low bit rate speech coding . it also compares the model of traditional dualistic excitation lpc vocoder and the multi - band excitation vocoder , and lucubrates the analytical method of frequency domain and time domain in the parameter extraction of multi - band excitation vocoding . secondly , based on the parameter extraction operation of keynote cycle , it adopts time domain in rough estimate operation of keynote and frequency domain in fine estimate operation of keynote , in according to the immediacy required in practice , to minish operation amount 本文阐述了一种基于fpga的多带激励语音编码器的研究与设计,首先介绍语音编码研究的发展状况以及低速率语音编码研究的意义,接着对比分析了传统二元激励lpc声码器模型和多带激励编码器模型,并深入研究了多带激励语音编码参数提取的频域和时域分析法,然后根据实际应用的实时性要求,为了减小运算量,在基音周期参数的提取的算法实现上,本文采用在时域进行基音粗估运算,在频域进行基音精细估计运算。
