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c26d0b4f29
Divide DT search range into 3 segments. Search central segment (near DT=0) first and try to decode the largest peak. Then find the largest peak in each of the surrounding segments and try to decode those only if the peak is larger than the one found in the central segment. Also re-indent ft4_decode.f90 and some other minor tweaks.
74 lines
1.9 KiB
Fortran
74 lines
1.9 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)
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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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ncand=0
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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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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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candidate(1,ncand)=fpeak
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candidate(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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return
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end subroutine getcandidates4
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