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Altera_Forum
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12 years ago

FFT MegaCore Function Output is not as expected

Hi, I have generated one FFT MegaCore Function in my FPGA design and simulated it using test bench. And the output is compared with the expected values; but they are not same. the parameter...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

For example:

I am getting the following in simulation:

source_real: 2659

source_imag: 3490

source_exp: -10

So as per my calculation:

out_real = source_real * 2^(exp) = 2659 * 2^-10 = 2.596679688

out_imag = source_imag * 2^(exp) = 3490 * 2^-10 = 3.408203125

So, Output = 10*log10(sqrt(out_real^2 + out_imag^2))

= 10* log10 (sqrt(6.742745399 + 11.61584854))

= 10* log10 (4.284692981)

= 6.319197081

But the value I am expecting here is -5.42

Could you please help me//