摘要
杜比AC-3的硬件解码器设计中,使用定点运算单元比浮点运算单元成本低,但是定点数动态范围小,尤其是IMDCT模块中需要大量乘加运算,多次迭代后误差会明显增大,因此需进行定点仿真来选择合适的字长以确保信噪比的要求。文中先对IMDCT算法进行分析,用推导来阐释IFFT实现IMDCT的方法。文中后半部分讲述对IMDCT进行定点仿真的方法,然后用Matlab的Simulink作为仿真平台,对不同字长的IMDCT模块进行仿真,并给出仿真结果。通过定点仿真不仅能得出不同规格的硬件AC-3解码器所需的运算字长,而且仿真模型的运算结果和中间数据可以为硬件的测试向量来验证硬件解码器的正确性。
Fixed -point decoder costs less than floating point decoder in hardware design, but its dynamic range is also less than that of the latter. For a large number of Multiply - add operations in IMDCT, SNR is the problem we must concerned. Thus, word - length should be set properly to improve SNR. IFFT is one of the fast algorithms for implementing IMDCT and the method is demonstrated by deduction in this paper. Fix - point simulation in Matlab is illustrated in this paper and the result is included. Word - Length can be selected for different kind of AC - 3 decoder. Also, the data in fixed -point simulation can be used to construct vectors for hardware testing.
出处
《计算机仿真》
CSCD
2007年第5期306-310,共5页
Computer Simulation
