subroutine filbig(dd,npts,f0,newdat,c4a,n4,sq0) ! Filter and downsample the real data in array dd(npts), sampled at 12000 Hz. ! Output is complex, sampled at 1378.125 Hz. use, intrinsic :: iso_c_binding use FFTW3 parameter (NSZ=3413) parameter (NFFT1=672000,NFFT2=77175) parameter (NZ2=1000) real*4 dd(npts) !Input data real*4 rca(NFFT1) complex ca(NFFT1/2+1) !FFT of input complex c4a(NFFT2) !Output data real*4 s(NZ2) real*8 df real halfpulse(8) !Impulse response of filter (one sided) complex cfilt(NFFT2) !Filter (complex; imag = 0) real rfilt(NFFT2) !Filter (real) ! integer*8 plan1,plan2,plan3 type(C_PTR) :: plan1,plan2,plan3 !Pointers to FFTW plans logical first ! include 'fftw3.f90' equivalence (rfilt,cfilt),(rca,ca) data first/.true./ data halfpulse/114.97547150,36.57879257,-20.93789101, & 5.89886379,1.59355187,-2.49138308,0.60910773,-0.04248129/ common/refspec/dfref,ref(NSZ) common/patience/npatience,nthreads save first,plan1,plan2,plan3 if(npts.lt.0) go to 900 !Clean up at end of program if(first) then nflags=FFTW_ESTIMATE if(npatience.eq.1) nflags=FFTW_ESTIMATE_PATIENT if(npatience.eq.2) nflags=FFTW_MEASURE if(npatience.eq.3) nflags=FFTW_PATIENT if(npatience.eq.4) nflags=FFTW_EXHAUSTIVE ! Plan the FFTs just once plan1=fftwf_plan_dft_r2c_1d(nfft1,rca,ca,nflags) plan2=fftwf_plan_dft_1d(nfft2,c4a,c4a,-1,nflags) plan3=fftwf_plan_dft_1d(nfft2,cfilt,cfilt,+1,nflags) ! Convert impulse response to filter function do i=1,nfft2 cfilt(i)=0. enddo fac=0.00625/nfft1 cfilt(1)=fac*halfpulse(1) do i=2,8 cfilt(i)=fac*halfpulse(i) cfilt(nfft2+2-i)=fac*halfpulse(i) enddo call fftwf_execute_dft(plan3,cfilt,cfilt) base=real(cfilt(nfft2/2+1)) do i=1,nfft2 rfilt(i)=real(cfilt(i))-base enddo df=12000.d0/nfft1 first=.false. endif ! When new data comes along, we need to compute a new "big FFT" ! If we just have a new f0, continue with the existing data in ca. if(newdat.ne.0) then call timer('FFTbig ',0) nz=min(npts,nfft1) rca(1:nz)=dd(1:nz) rca(nz+1:)=0. call fftwf_execute_dft_r2c(plan1,rca,ca) call timer('FFTbig ',1) call timer('flatten ',0) ib=0 do j=1,NSZ ia=ib+1 ib=nint(j*dfref/df) fac=sqrt(min(30.0,1.0/ref(j))) ca(ia:ib)=fac*conjg(ca(ia:ib)) enddo call timer('flatten ',1) endif ! NB: f0 is the frequency at which we want our filter centered. ! i0 is the bin number in ca closest to f0. call timer('loops ',0) i0=nint(f0/df) + 1 nh=nfft2/2 do i=1,nh !Copy data into c4a and apply j=i0+i-1 !the filter function if(j.ge.1 .and. j.le.nfft1/2+1) then c4a(i)=rfilt(i)*ca(j) else c4a(i)=0. endif enddo do i=nh+1,nfft2 j=i0+i-1-nfft2 ! if(j.lt.1) j=j+nfft1 !nfft1 was nfft2 if(j.ge.1) then c4a(i)=rfilt(i)*ca(j) else c4a(i)=rfilt(i)*conjg(ca(2-j)) endif enddo nadd=nfft2/NZ2 i=0 do j=1,NZ2 s(j)=0. do n=1,nadd i=i+1 s(j)=s(j) + real(c4a(i))**2 + aimag(c4a(i))**2 enddo enddo call pctile(s,NZ2,30,sq0) call timer('loops ',1) ! Do the short reverse transform, to go back to time domain. call timer('FFTsmall',0) call fftwf_execute_dft(plan2,c4a,c4a) call timer('FFTsmall',1) n4=min(npts/8,nfft2) return 900 call fftwf_destroy_plan(plan1) call fftwf_destroy_plan(plan2) call fftwf_destroy_plan(plan3) return end subroutine filbig