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Re: FFT question

Reply posted 3 months ago (06/24/2022)
For reference schema of IQ tayloe mixer.All source code is on https://github.com/paulh002/sdrberry and https://github.com/paulh002/SoapyHifiBerry#include <fftw3.h>#include...

Re: FFT question

Reply posted 3 months ago (06/24/2022)
Yes, you're right. If you do software and hardware at the same time is asking for trouble :)It was software after all I had to swap the output of the fft. Thanks...

Re: FFT question

Reply posted 3 months ago (06/24/2022)
I think your correct after all

Re: FFT question

Reply posted 3 months ago (06/24/2022)
ello Rick,Thanks for your explanation. So if my fft is generating a mirror image like your first picture I am executing a real value fft? I was expecting to execute...

Re: FFT question

Reply posted 3 months ago (06/23/2022)
Hello Philip,Thanks, I think that a good idea. I will make a generator and let it sweep and see what the FFT does. But the reason that I think it is not the IQ signal...

Re: FFT question

Reply posted 3 months ago (06/23/2022)
Yes, they are. 1 clock at 4 times fs and a divide by 4 to generate 2 clocks with 90 degree difference

Re: FFT question

Reply posted 3 months ago (06/23/2022)
Complex fft, I use liquid dsp for fft which uses fftw3

Re: FFT question

Reply posted 3 months ago (06/23/2022)
The clocks are in 90 degree phase. I use a divider to generate phase and 90 degree phase signal. But the answer from Kaz is not correct. The negative frequencies...

Re: FFT question

Reply posted 3 months ago (06/23/2022)
Ok, thanks.Will do some measurements, maybe something wrong with the IQ signal. Thanks for your reply. 

Re: FFT question

Reply posted 3 months ago (06/23/2022)
So in-principle I can display the spectrum from -fs/2 till +fs/2 if the IQ numbers are correct. That is 90 degree phase shift. 

Re: FFT question

Reply posted 3 months ago (06/23/2022)
That's not what I see, I only see 192/2 of the spectrum. 

FFT question

New thread started 3 months ago
Hello,I am sampling, at 192 Khz each channel, a radio signal with a IQ mixer and 2 ADC's. I combine the values into complex numbers. Literature tells that using...

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