RADIX-2 FFT ALGORITHMS
DECIMATION IN TIME (DITFFT)
There are three properties of twiddle factor WN
N point sequence x(n) be splitted into two N/2 point data sequences f1(n) and f2(n). f1(n) contains even numbered samples of x(n) and f2(n) contains odd numbered samples of x(n). This splitted operation is called decimation. Since it is done on time domain sequence it is called “Decimation in Time”. Thus
f1(m)=x(2m) where n=0,1,………….N/2-1
f2(m)=x(2m+1) where n=0,1,………….N/2-1
N point DFT is given as
Since the sequence x(n) is splitted into even numbered and odd numbered samples, thus
Fig 1 shows that 8-point DFT can be computed directly and hence no reduction in computation.
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