09-09-2009 10:24 AM
I am usinf FFT IP core V6.0. When I took the FFT of following data points
1.1 2.2 3.3 4.4 1.1 2.2 3.3 4.4
in floating point format using the transform length of eight, i get the following Result
22 0 -4.4000 - 4.4000i 0 -4.4000 0 -4.4000 + 4.4000i 0
whereas MATLAB gives the following Result
22 0 -4.4000 + 4.4000i 0 -4.4000 0 -4.4000 - 4.4000i 0
The problem is that the signs of imaginary part is inverted. I have check it in both fixed point and floating formats, but problem remains the same, the signs of the imaginary parts are inverted, when we compare the results of MATLAB with that of FFT core.
Solved! Go to Solution.
09-22-2009 02:39 AM
I think you've done an IFFT instead of an FFT.
Check the 'fwd_inv' input; it must be set to 0 for inverse transform and 1 forforward transform
DSP Specialist EMEA
09-28-2009 05:09 AM
FFT datasheet includes waveforms how initialization should be done. This is the first step. Second, you need to add 3 clocks delay between every input. How do you read output?
10-17-2011 06:20 PM
i use the fft ipcore to compute fft and ifft
but both the result are fft data
i have set the fwd_inv both 0 and 1
the result is fft result
can you tell me some reason
01-30-2012 02:59 AM
when im simulating fft core 7.1, im getting unexpected results....
i am not able to understand where i'v done wrong ...
i'v added some simulation results...
if u can plz provide the correct code or help me to get correct output...