一种改进的定点FFT溢出处理方法

Improved overflow disposal method for fixed-point FFT

针对定点快速傅里叶变换(FFT)在运算准确度与实现复杂度方面不能兼顾的问题,对定点FFT算法的溢出检测方法进行了研究,并在Welch方法的基础上,提出了新的溢出检测方法。在所提方法中,将溢出检测模块放在每个蝶形运算开始的位置,对将要参加本次运算的输入数据进行溢出检测,且每个蝶形中只需一次检测。与Welch的方法相比,所提方法误差小,仿真结果表明,当平均误差(均方根误差与运算结果均方根的比值)或信号量化噪声比相同时,所提方法可节约一定的比特数。

For the problem of fixed-point Fast Fourier transform （FFT） between accuracy of algorithm and complexity of realization,a novel method for overflow processing is proposed based on Welch＇s methods.In the proposed method,overflow detection module is put in the beginning of each butterfly,and the inputs of this butterfly are detected,in addition,only one test is needed in each butterfly.From the results of simulation,compared with Welch＇s methods,it can be concluded that the proposed method could save a number of bits for achieving the same performance in the same simulation environment.The proposed method is not only accuracy in calculation but also simple in realization.