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DFT problemby souhal.67
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#1
Feb2812, 12:27 PM

P: 7

I have a f(n*t) vs t data areay how to find out its (DFT) fourier transform in c. I find every time that every program needs its real and imaginarry part. but i have only magnitude. please help me out to find DFT of these data .



#2
Feb2912, 06:08 AM

Sci Advisor
Thanks
PF Gold
P: 12,238

If your data is all real then why not put the imaginary values as zero?



#3
Mar312, 01:26 AM

P: 7

then how i get the value of omega for ploting



#4
Mar312, 01:30 AM

P: 7

DFT problem
after sampling I have value of t & X(t) like
375.020000 0.754661 375.030000 0.755227 375.040000 0.755841 375.050000 0.756501 375.060000 0.757207 375.070000 0.757960 375.080000 0.758759 375.090000 0.759604 375.100000 0.760494 375.110000 0.761431 375.120000 0.762414 375.130000 0.763442 375.140000 0.764515 375.150000 0.765633 375.160000 0.766797 375.170000 0.768005 375.180000 0.769258 I would like to find DFT and I need omega/freq and X(W) value please help me Thank you 


#5
Mar312, 01:30 AM

P: 7

after sampling I have value of t & X(t) like
375.020000 0.754661 375.030000 0.755227 375.040000 0.755841 375.050000 0.756501 375.060000 0.757207 375.070000 0.757960 375.080000 0.758759 375.090000 0.759604 375.100000 0.760494 375.110000 0.761431 375.120000 0.762414 375.130000 0.763442 375.140000 0.764515 375.150000 0.765633 375.160000 0.766797 375.170000 0.768005 375.180000 0.769258 I would like to find DFT and I need omega/freq and X(W) value please help me Thank you 


#6
Mar312, 03:17 AM

Sci Advisor
Thanks
PF Gold
P: 12,238

How much do you know about discrete Fourier transforms? What are you trying to find out from the data?



#7
Mar312, 03:21 AM

P: 7

Thank you for reply. I want to find out a frequency Vs Amplitude graph



#8
Mar312, 03:23 AM

P: 7

I want to find out time vs Amplitude to frequency vs Amplitude of a signal



#9
Mar312, 03:24 AM

Sci Advisor
Thanks
PF Gold
P: 12,238

And what does DFT do? (I want you to work a bit for this. ;) )



#10
Mar312, 03:31 AM

P: 7

I have a collage project and I have a system out put I must make a program to find out system's frequency response of numerically.



#11
Mar312, 03:40 AM

Sci Advisor
Thanks
PF Gold
P: 12,238

You didn't say what the DFT does. You have asked a question that suggests you have no idea. I could tell you anything and you would believe me. You need to understand about the process.
If you want an answer then put some data in for a familiar waveform for which you know the frequency spectrum. Try some sine waves with different periods. 


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