You didn't mention the radix of each stage. Divide by 4 is too much if it is a radix2 butterfly. If it is radix 2, the gain is at most 2, not
- The max output from an FFT occurs when all the > Hello,
> I have constructed a 256 pt complex fft. My scaling is causing
> problems as the outputs from each stage are divided by 4 to avoid
> overflow. The input data and the twiddle factor coeffs are 16 bits
> wide (Q15). My problem is that when the data arrives at the last two
> butterfly stages of the FFT, it is non-existant, due to all the
> scaling beforehand. All inputs to these stages are zero. Thus I get
> nothing at the output.
>
> How can I work around this?
>
> Many thanks
>
> Bob
--
--Ray Andraka, P.E. President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950 email snipped-for-privacy@andraka.com
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