Re: [Discuss-gnuradio] Scaling down IFFT values

[Marcus Müller]

Hi you!
>Any pointer on where should I make the change?
Yes. Do it before preambling!
The inverse dft is a linear operation; it doesn't really matter whether
you scale before or after. Note though that the IFFT as we use it adds a
sqrt(length_of_fft) factor, so account for that by dividing your scaling
factor by it.

Greetings,
Marcus

On 16.10.2014 13:35, zealdeal wrote:
> Hi All,
>
> I need to scale down the OFDM transmission signal in time domain, after IFFT
> is done, so that, all the values are within the range -1 to 1. But, I cant
> simply add one more "scaling" block after cp_adder in
>
> self.connect(self.preambles, self.ifft, self.cp_adder, self.scale, self) 
> (file: ofdm,py)
>
> as it will scale down the preamble also, leading to non-recognition of
> packet at receiver end.
>
> Any pointer on where should I make the change?
>
>
>
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