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楼主 |
发表于 2014-1-19 22:09:01
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谢谢!和source_exp无关吗?
用户手册:
Unlike an FFT block that uses floating point arithmetic, a block-floating-point FFT
block does not provide an input for exponents. Internally, a complex value integer
pair is represented with a single scale factor that is typically shared among other
complex value integer pairs. After each stage of the FFT, the largest output value is
detected and the intermediate result is scaled to improve the precision. The exponent
records the number of left or right shifts used to perform the scaling. As a result, the
output magnitude relative to the input level is:
output*2-exponent
For example, if exponent = –3, the input samples are shifted right by three bits, and
hence the magnitude of the output is output*23.
我在excel里做了一个sin函数,用excel自带的傅里叶转换后得出的频率图基本是对的。将信号数据拷贝到FFT_1_real_input.txt(FFT_1_imag_input.txt全为0)后用ModelSim仿真得出的曲线感觉不对。
FFT是16位1024点连续Streaming。第一次搞这个,头绪都没有。
见图:
仿真流程貌似正确。
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