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73 lines
1.7 KiB
Fortran
73 lines
1.7 KiB
Fortran
subroutine getcandidates4(id,fa,fb,syncmin,nfqso,maxcand,savg,candidate, &
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ncand,sbase)
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include 'ft4_params.f90'
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real s(NH1,NHSYM)
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real savg(NH1),savsm(NH1)
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real sbase(NH1)
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real x(NFFT1)
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real window(NFFT1)
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complex cx(0:NH1)
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real candidate(3,maxcand)
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integer*2 id(NMAX)
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integer indx(NH1)
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integer ipk(1)
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equivalence (x,cx)
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logical first
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data first/.true./
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save first,window
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if(first) then
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first=.false.
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pi=4.0*atan(1.)
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window=0.5*(1-cos(pi*(/(i,i=1,NFFT1)/)/(NFFT1/2.0)))
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window=window**2
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endif
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! Compute symbol spectra, stepping by NSTEP steps.
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savg=0.
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tstep=NSTEP/12000.0
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df=12000.0/NFFT1 !3.125 Hz
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fac=1.0/300.0
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do j=1,NHSYM
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ia=(j-1)*NSTEP + 1
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ib=ia+NFFT1-1
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if(ib.gt.NMAX) exit
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x=fac*id(ia:ib)*window
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call four2a(x,NFFT1,1,-1,0) !r2c FFT
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do i=1,NH1
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s(i,j)=real(cx(i))**2 + aimag(cx(i))**2
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enddo
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savg=savg + s(1:NH1,j) !Average spectrum
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enddo
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savsm=0.
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do i=8,NH1-7
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savsm(i)=sum(savg(i-7:i+7))/15.
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enddo
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nfa=fa/df
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nfb=fb/df
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np=nfb-nfa+1
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indx=0
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call indexx(savsm(nfa:nfb),np,indx)
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xn=savsm(nfa+indx(nint(0.3*np)))
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savsm=savsm/xn
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ncand=0
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f_offset = -1.5*12000/512
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do i=1,maxcand
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ipk=maxloc(savsm(nfa:nfb))
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ip=nfa-1+ipk(1)
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xmax=savsm(ip)
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savsm(max(1,ip-8):min(NH1,ip+8))=0.0
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if(xmax.ge.syncmin) then
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ncand=ncand+1
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candidate(1,ncand)=ip*df+f_offset
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candidate(2,ncand)=-99.9
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candidate(3,ncand)=xmax
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else
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exit
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endif
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enddo
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return
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end subroutine getcandidates4
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