- #1

- 431

- 5

## Main Question or Discussion Point

I have a working DFT and FFT now that I coded in a program ..

now from testing I can see that with both the FFT and the DFT if I just graph the Imaginary number I will get the right frequency

for example:

F[t] = 10 Sin((2 * PI * 2000 *t)/8000) 0 <t <1024

will get me

a frequency

2000 Hz and 6000 Hz now I do know that 6000 Hz is the - frequency in the sin wave

but I a graph my Real numbers I get

0 Hz

4000Hz

Why is that ?

should I only use my imaginary values and for get about my real value ?

also my magnitude for all the Frequencies are the same 65535 can I get something from that ?

now from testing I can see that with both the FFT and the DFT if I just graph the Imaginary number I will get the right frequency

for example:

F[t] = 10 Sin((2 * PI * 2000 *t)/8000) 0 <t <1024

will get me

a frequency

2000 Hz and 6000 Hz now I do know that 6000 Hz is the - frequency in the sin wave

but I a graph my Real numbers I get

0 Hz

4000Hz

Why is that ?

should I only use my imaginary values and for get about my real value ?

also my magnitude for all the Frequencies are the same 65535 can I get something from that ?