how to implement 7000pt radix-2 fft

[ajayreddybireddy]

hello friends,

can any person tell me ' how to implement 7000pt radix-2 fft?' without using in matlab built function

 

[Communications_Engineer]

Re: fft implementation

fft DIT or fft DIF?

I suggest you have read of the DSP book by Ifeachor. It has a C program for fft in it (if my memory serves me right)

Anyway, if you know the equation for dft, you can create a function for it.

 

[zorx]

Re: fft implementation

Matlab, like many other packages, uses well proven code for FFT from
FFTW Home Page
Go there and download the source code.

 

[ajayreddybireddy]

Re: fft implementation

sure I'll go through that book

because of advantages with decimation in time, I do prefer DIT

and give me any M-file for understanding the basic algorithm to implement that much of large point FFT's

 

[Communications_Engineer]

Re: fft implementation

MATLAB Central - Search Results: tag:"fft"

You might have some idea from there. But still, Ifeachor's book will help you immensely

 

[uk.engr]

Re: fft implementation

Hi,
I have made the simulation code for SC-FDMA, I want evaluate to its PAPR, how should I calculate it. Please help, here I am calculating in this way:
for ii = 1:OFDMSym
outputiFFT=Transmitted_data(ii,;
meanSquareValue = outputiFFT*outputiFFT'/length(outputiFFT);
peakValue = max(outputiFFT.*conj(outputiFFT));
paprSymbol(ii) = peakValue/meanSquareValue;
end
paprSymboldB = 10*log10(paprSymbol);
[n x] = hist(paprSymboldB,[0:0.5:15]);
plot(x,cumsum/OFDMSym,'LineWidth',4)

but it results in straight line (wrong output).......

kindly tell me

 

[lostinxlation]

Re: fft implementation

Shouldn't the number of point be a power of 2 when you run radix-2 algorithm ? Or you just run zero stuffing to the nearest power of 2.
The easiest way is reversing the bit order of time domain index, applying 2 point butterfly operation on two data next each other, and then 4 points, then 8 points..... till your target point with butterfly operation.

Richard Lyons' book explains it in very plain and easy way.

 

[uk.engr]

Assalam o Aleikum (Hello/Hi),

Thank you lostinxlation.