中文摘要：

主要研究定点、块浮点和浮点运算机制下,频域抽取基4算法的精度问题。首先分析了定点、块浮点、浮点等运算机制下,基4算法基本运算单元中数据不同表现形式及输出截位规则。然后利用MATLAB平台建立了定点与块浮点FFT仿真模型,以噪信比作为FFT输出精度指标,研究输出精度与输入信号范围、算法参数之间的关系。仿真表明,输入为随机序列时,定点与块浮点FFT输出噪信比与输入信号幅值范围、输入序列长度及算法输入位宽有关。此结论可用以解决实际工程中小信号频谱失真问题,在工程分析与设计中具有重要参考价值。

英文摘要：

Accuracy in radix 4 decimation in frequency （DIF） algorithm is researched with different operation mechanisms. We ana- lyze different data forms and roundoff rules of radix 4 operation unit with fixed-point, block floating point and floating point. A simulation model is established on MATLAB platform for operation mechanisms including fixed-point and block floating point. In this model, accuracy is measured by noise signal ratio. The result shows that, when the input is rand sequence , the noise signal ratio is effected by input length and scale and input width of algorithm. With the simulation result, we solved the spectral distortion with weak signal in practice. Consequently this scheme has better valve in practice.