Bit reverse order Technique in FFT Can anyone tell me how does bit reversal order technique works for FFT when you are trying to break down the FFT to small sizes. Like I want to only for the when the index is odd because that involve some reverse carry propagation, but when the index is even you just add N/2 to it to get your reverse index r. An example of N=8 would be perfect if someone can explain me.
If I understand your question correctly you want this (index | binary | bit rev. | bit rev. index):

$$
0\quad        000\quad      000\quad 0\\
1\quad        001\quad      100\quad 4\\
2\quad        010\quad      010\quad 2\\
3\quad        011\quad      110\quad 6\\
4\quad        100\quad      001\quad 1\\
5\quad        101\quad      101\quad 5\\
6\quad        110\quad      011\quad 3\\
7\quad        111\quad      111\quad 7\\
$$