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117 lines
3.0 KiB
Fortran
117 lines
3.0 KiB
Fortran
subroutine get_ft4_bitmetrics(cd,bitmetrics,badsync)
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include 'ft4_params.f90'
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parameter (NSS=NSPS/NDOWN,NDMAX=NMAX/NDOWN)
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complex cd(0:NN*NSS-1)
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complex cs(0:3,NN)
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complex csymb(NSS)
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integer icos4a(0:3),icos4b(0:3),icos4c(0:3),icos4d(0:3)
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integer graymap(0:3)
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integer ip(1)
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logical one(0:255,0:7) ! 256 4-symbol sequences, 8 bits
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logical first
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logical badsync
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real bitmetrics(2*NN,3)
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real s2(0:255)
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real s4(0:3,NN)
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data icos4a/0,1,3,2/
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data icos4b/1,0,2,3/
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data icos4c/2,3,1,0/
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data icos4d/3,2,0,1/
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data graymap/0,1,3,2/
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data first/.true./
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save first,one
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if(first) then
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one=.false.
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do i=0,255
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do j=0,7
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if(iand(i,2**j).ne.0) one(i,j)=.true.
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enddo
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enddo
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first=.false.
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endif
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do k=1,NN
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i1=(k-1)*NSS
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csymb=cd(i1:i1+NSS-1)
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call four2a(csymb,NSS,1,-1,1)
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cs(0:3,k)=csymb(1:4)
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s4(0:3,k)=abs(csymb(1:4))
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enddo
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! Sync quality check
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is1=0
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is2=0
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is3=0
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is4=0
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badsync=.false.
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ibmax=0
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do k=1,4
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ip=maxloc(s4(:,k))
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if(icos4a(k-1).eq.(ip(1)-1)) is1=is1+1
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ip=maxloc(s4(:,k+33))
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if(icos4b(k-1).eq.(ip(1)-1)) is2=is2+1
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ip=maxloc(s4(:,k+66))
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if(icos4c(k-1).eq.(ip(1)-1)) is3=is3+1
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ip=maxloc(s4(:,k+99))
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if(icos4d(k-1).eq.(ip(1)-1)) is4=is4+1
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enddo
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nsync=is1+is2+is3+is4 !Number of correct hard sync symbols, 0-16
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if(nsync .lt. 8) then
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badsync=.true.
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return
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endif
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do nseq=1,3 !Try coherent sequences of 1, 2, and 4 symbols
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if(nseq.eq.1) nsym=1
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if(nseq.eq.2) nsym=2
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if(nseq.eq.3) nsym=4
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nt=2**(2*nsym)
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do ks=1,NN-nsym+1,nsym !87+16=103 symbols.
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amax=-1.0
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do i=0,nt-1
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i1=i/64
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i2=iand(i,63)/16
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i3=iand(i,15)/4
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i4=iand(i,3)
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if(nsym.eq.1) then
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s2(i)=abs(cs(graymap(i4),ks))
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elseif(nsym.eq.2) then
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s2(i)=abs(cs(graymap(i3),ks)+cs(graymap(i4),ks+1))
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elseif(nsym.eq.4) then
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s2(i)=abs(cs(graymap(i1),ks ) + &
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cs(graymap(i2),ks+1) + &
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cs(graymap(i3),ks+2) + &
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cs(graymap(i4),ks+3) &
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)
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else
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print*,"Error - nsym must be 1, 2, or 4."
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endif
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enddo
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ipt=1+(ks-1)*2
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if(nsym.eq.1) ibmax=1
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if(nsym.eq.2) ibmax=3
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if(nsym.eq.4) ibmax=7
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do ib=0,ibmax
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bm=maxval(s2(0:nt-1),one(0:nt-1,ibmax-ib)) - &
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maxval(s2(0:nt-1),.not.one(0:nt-1,ibmax-ib))
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if(ipt+ib.gt.2*NN) cycle
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bitmetrics(ipt+ib,nseq)=bm
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enddo
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enddo
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enddo
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bitmetrics(205:206,2)=bitmetrics(205:206,1)
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bitmetrics(201:204,3)=bitmetrics(201:204,2)
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bitmetrics(205:206,3)=bitmetrics(205:206,1)
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call normalizebmet(bitmetrics(:,1),2*NN)
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call normalizebmet(bitmetrics(:,2),2*NN)
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call normalizebmet(bitmetrics(:,3),2*NN)
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return
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end subroutine get_ft4_bitmetrics
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