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117 lines
2.5 KiB
Fortran
117 lines
2.5 KiB
Fortran
subroutine sfox_sync(iwave,fsample,isync,f,t)
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use sfox_mod
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parameter (NSTEP=8)
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integer*2 iwave(0:NMAX-1)
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integer isync(44)
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integer ipeak(2)
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complex, allocatable :: c(:) !Work array
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real x(171)
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real, allocatable :: s(:,:) !Symbol spectra, stepped by NSTEP
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real, allocatable :: savg(:) !Average spectrum
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real, allocatable :: ccf(:,:)
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! character*1 line(-15:15),mark(0:6),c1
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! data mark/' ','.','-','+','X','$','#'/
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nfft=nsps
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nh=nfft/2
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istep=NSPS/NSTEP
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jz=(13.5*fsample)/istep
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df=fsample/nfft
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dtstep=istep/fsample
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fsync=1500.0-bw/2
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ftol=20.0
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ia=nint((fsync-ftol)/df)
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ib=nint((fsync+ftol)/df)
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lagmax=1.0/dtstep
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lag1=-lagmax
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lag2=lagmax
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x=0.
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do i=1,NS
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x(isync(i))=1.0
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enddo
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allocate(s(0:nh/2,jz))
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allocate(savg(0:nh/2))
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allocate(c(0:nfft-1))
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allocate(ccf(ia:ib,lag1:lag2))
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s=0.
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savg=0.
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fac=1.0/nfft
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! Compute symbol spectra with df=baud/2 and NSTEP steps per symbol.
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do j=1,jz
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i1=(j-1)*istep
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i2=i1+nsps-1
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k=-1
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do i=i1,i2,2 !Load iwave data into complex array c0, for r2c FFT
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xx=iwave(i)
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yy=iwave(i+1)
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k=k+1
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c(k)=fac*cmplx(xx,yy)
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enddo
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c(k+1:)=0.
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call four2a(c,nfft,1,-1,0) !r2c FFT
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do i=1,nh/2
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s(i,j)=real(c(i))**2 + aimag(c(i))**2
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savg(i)=savg(i) + s(i,j)
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enddo
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enddo
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savg=savg/jz
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!###
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ccfbest=0.
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ibest=0
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lagpk=0
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lagbest=0
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j0=0.5/dtstep !Nominal start-signal index
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do i=ia,ib
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ccfmax=0.
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do lag=lag1,lag2
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ccft=0.
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do kk=1,NS
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k=isync(kk)
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n=NSTEP*(k-1) + 1
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j=n+lag+j0
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if(j.ge.1 .and. j.le.jz) ccft=ccft + s(i,j)
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enddo ! kk
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ccft=ccft - NS*savg(i)
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ccf(i,lag)=ccft
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if(ccft.gt.ccfmax) then
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ccfmax=ccft
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lagpk=lag
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endif
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enddo ! lag
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if(ccfmax.gt.ccfbest) then
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ccfbest=ccfmax
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ibest=i
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lagbest=lagpk
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endif
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enddo ! i
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ipeak=maxloc(ccf)
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ipk=ipeak(1)-1+ia
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jpk=ipeak(2)-1+lag1
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call peakup(ccf(ipk-1,jpk),ccf(ipk,jpk),ccf(ipk+1,jpk),dxi)
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call peakup(ccf(ipk,jpk-1),ccf(ipk,jpk),ccf(ipk,jpk+1),dxj)
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f=ibest*df + bw/2 + dxi*df
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t=lagbest*dtstep + dxj*dtstep
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! write(*,4100) ibest,lagbest,f,dxi*df,t,dxj*dtstep
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!4100 format(2i6,2f10.1,2f10.3)
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! print*,'aaa',ibest,lagbest
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! do lag=lag1,lag2
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! write(51,3051) lag*dtstep,ccf(ibest,lag)
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!3051 format(2f12.4)
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! enddo
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return
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end subroutine sfox_sync
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