The objective of this experiment was to develop a function for calculating DFT of N-point signal.
This experiment was performed in C. Two separate code were written, one for 4point and one for 8 point DFT. 8point DFT was calculated using 4point DFT code.
A signal for N=4, was taken and its DFT was found. Same signal was converted to N=8 using zero padding.
The DFT output H[k] was same, as that for N=4 for even values of k.
Also H[k] is periodic due to nature of twiddle factor.
Magnitude spectrum for N=4 and N=8 were drawn.
https://drive.google.com/open?id=0B8Ks3rz0S_nzMmlUZGw3aV9wbXM
This experiment was performed in C. Two separate code were written, one for 4point and one for 8 point DFT. 8point DFT was calculated using 4point DFT code.
A signal for N=4, was taken and its DFT was found. Same signal was converted to N=8 using zero padding.
The DFT output H[k] was same, as that for N=4 for even values of k.
Also H[k] is periodic due to nature of twiddle factor.
Magnitude spectrum for N=4 and N=8 were drawn.
https://drive.google.com/open?id=0B8Ks3rz0S_nzMmlUZGw3aV9wbXM
Twiddle factor W describes nothing but a rotating vector.
ReplyDeleteIt is because of the periodic nature. Repeats the same values after interval of 2*pi
ReplyDeletethe zero padding function was provided in the code right?
ReplyDeletein DFT There are N^2 complex multiplication.
ReplyDeleteIt is used in real time processing as we don't require all the inputs for getting the output
ReplyDelete