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87 lines
2.3 KiB
Fortran
87 lines
2.3 KiB
Fortran
subroutine getcandidates4(dd,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(2,maxcand),candidatet(2,maxcand)
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real dd(NMAX)
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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.
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call nuttal_window(window,NFFT1)
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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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df=12000.0/NFFT1
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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*dd(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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savg=savg/NHSYM
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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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if(nfa.lt.nint(200.0/df)) nfa=nint(200.0/df)
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nfb=fb/df
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if(nfb.gt.nint(4910.0/df)) nfb=nint(4910.0/df)
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call ft4_baseline(savg,nfa,nfb,sbase)
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if(any(sbase(nfa:nfb).le.0)) return
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savsm(nfa:nfb)=savsm(nfa:nfb)/sbase(nfa:nfb)
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f_offset = -1.5*12000.0/NSPS
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ncand=0
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candidatet=0
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do i=nfa+1,nfb-1
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if(savsm(i).ge.savsm(i-1) .and. savsm(i).ge.savsm(i+1) .and. &
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savsm(i).ge.syncmin) then
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den=savsm(i-1)-2*savsm(i)+savsm(i+1)
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del=0.
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if(den.ne.0.0) del=0.5*(savsm(i-1)-savsm(i+1))/den
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fpeak=(i+del)*df+f_offset
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if(fpeak.lt.200.0 .or. fpeak.gt.4910.0) cycle
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speak=savsm(i) - 0.25*(savsm(i-1)-savsm(i+1))*del
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ncand=ncand+1
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candidatet(1,ncand)=fpeak
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candidatet(2,ncand)=speak
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if(ncand.eq.maxcand) exit
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endif
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enddo
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candidate=0
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nq=count(abs(candidatet(1,1:ncand)-nfqso).le.20.0)
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n1=1
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n2=nq+1
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do i=1,ncand
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if(abs(candidatet(1,i)-nfqso).le.20.0) then
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candidate(1:2,n1)=candidatet(1:2,i)
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n1=n1+1
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else
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candidate(1:2,n2)=candidatet(1:2,i)
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n2=n2+1
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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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