Hermitian symmetry for IFFT

Hi all

I am strugling to get real valued output from a IFFT from a complex valued
input. I know if the complex input is aligned using hermitian symmetry, the
output must be only real valued.

My question is how to align the values hermitially. For example:

If my input is:
1+2j; 2+3j; 5+j; 7+2j

How do one align this hermitally?
I have tried the following two approaches but neither seem to work.

1+2j; 2+3j; 5+j; 7+2j; 7+2j; 5+j; 2+3j; 1+2j;

and
1+2j; 2+3j; 5+j; 7+2j; 5+j; 2+3j; 1+2j;


Does anyone know...

Thanks
Jaco


		
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s22139584 wrote:
> Hi all
>
> I am strugling to get real valued output from a IFFT from a complex valued
> input. I know if the complex input is aligned using hermitian symmetry, the
> output must be only real valued.

Use an IFFT that is designed for hermitian symmetric input. In that
case, you don't have to worry about it yourself.


> My question is how to align the values hermitially. For example:
>
> If my input is:
> 1+2j; 2+3j; 5+j; 7+2j
>
> How do one align this hermitally?
> I have tried the following two approaches but neither seem to work.
>
> 1+2j; 2+3j; 5+j; 7+2j; 7+2j; 5+j; 2+3j; 1+2j;

Remember that an N-point real FFT gives you N/2+1 distinct complex
values (where the first and the last value is real). So a Hermitian
symmetric output from an 8-point real FFT might look like this:

1; 2+3j; 5+j; 7+2j; 9; 7-2j; 5-j; 2-3j;

The imaginary part of the IFFT array will contain some numerical noise
that you can ignore.

Regards,
Andor