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