From a cursory glance it looks like you are creating (hermetian) symmetry in
your data with phy [whatever][whatever]
I would suggest reviewing the properties of the discrete Fourier transform.
On May 16, 2019, 9:11 PM -0700, Koyel Das (Vehere) via USRP-users
<usrp-users@lists.ettus.com>, wrote:
> Hi Marcus,
>
> I emailed to f...@fftw.org but got no response so I thought some USRP users
> might also be using this library and hence I may get a response. That is why.
>
> Regards,
> Koyel Das
> Senior – Product Engineer
> Vehere | Proactive Communications Intelligence & Cyber Defence
> M: +919051132173 | T: +91 33 40545454 | F: +91 33 40545455 | W: www.vehere.com
>
>
>
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> From: USRP-users <usrp-users-boun...@lists.ettus.com> on behalf of Marcus D.
> Leech via USRP-users <usrp-users@lists.ettus.com>
> Sent: Friday, May 17, 2019 9:27:34 AM
> To: usrp-users@lists.ettus.com
> Subject: Re: [USRP-users] problem with fftw_plan_dft_2d
>
> On 05/16/2019 11:52 PM, Koyel Das (Vehere) via USRP-users wrote:
> > Hi,
> >
> > Following is a snapshot of my code using fftw_plan_dft_2d. I am getting all
> > zeros in the imaginary part of fft (in the printf command of the following
> > code:last line). The real part is correct.Could you please tell where am I
> > going wrong?
> >
> > fftw_complex *imageOutputPlane=VDDSAlgorithm::imageOutPlane;
> > fftw_complex *imageInputPlane=VDDSAlgorithm::imageInputPlane;
> > unsigned char*imageData=VDDSAlgorithm::imageData;
> > unsigned char*imageDataFinal=VDDSAlgorithm::imageDataFinal;
> >
> >
> > memset(imageInputPlane,0x0,IMAGE_DIMENSION*IMAGE_DIMENSION*sizeof(fftw_complex));
> >
> > memset(imageOutputPlane,0x0,IMAGE_DIMENSION*IMAGE_DIMENSION*sizeof(fftw_complex));
> > memset(imageData,0x0,IMAGE_DIMENSION*IMAGE_DIMENSION);
> >
> > for(size_t count=0;count<TOTAL_BASE_LINE;count++){
> >
> > imageInputPlane[(int)round(IMAGE_DIMENSION/2+diffX[count])*IMAGE_DIMENSION+(int)round(IMAGE_DIMENSION/2-diffY[count])][0]=phy[count][0];
> >
> > imageInputPlane[(int)round(IMAGE_DIMENSION/2+diffX[count])*IMAGE_DIMENSION+(int)round(IMAGE_DIMENSION/2-diffY[count])][1]=-(phy[count][1]);
> >
> > imageInputPlane[(int)round(IMAGE_DIMENSION/2-diffX[count])*IMAGE_DIMENSION+(int)round(IMAGE_DIMENSION/2+diffY[count])][0]=phy[count][0];
> >
> > imageInputPlane[(int)round(IMAGE_DIMENSION/2-diffX[count])*IMAGE_DIMENSION+(int)round(IMAGE_DIMENSION/2+diffY[count])][1]=phy[count][1];
> > }
> >
> > fftLock.lock();
> > fftw_plan planeX=fftw_plan_dft_2d(IMAGE_DIMENSION,IMAGE_DIMENSION,
> > imageInputPlane, imageOutputPlane, FFTW_FORWARD, FFTW_ESTIMATE);
> > fftw_execute(planeX);
> > fftw_destroy_plan(planeX);
> > fftLock.unlock();
> >
> >
> > double max=0;
> > for(size_t row=0;row<IMAGE_DIMENSION;row++){
> > for(size_t col=0;col<IMAGE_DIMENSION;col++){
> > if(col==0)printf("\n");
> > if(col<100){
> >
> > printf("(%lf,%lf)",imageOutputPlane[row*IMAGE_DIMENSION+col][0],imageOutputPlane[row*IMAGE_DIMENSION+col][1]);
> > }
> >
> > }
> > }
> >
> > Regards,
> > Koyel Das
> > Senior – Product Engineer
> > Vehere | Proactive Communications Intelligence & Cyber Defence
> > M: +919051132173 | T: +91 33 40545454 | F: +91 33 40545455 | W:
> > www.vehere.com
> I'm having a hard time seeing how this is related to UHD and USRPs.
>
> There's probably a support forum for FFTW out there that would be more
> helpful than here.
>
>
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