mirror of https://github.com/saitohirga/WSJT-X.git
Tweaks to syncmsk144 - improve performance for short pings.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6758 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke
parent
c7344e0441
commit
b91a9a782b
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@ -109,6 +109,10 @@ subroutine syncmsk144(cdat,npts,pchk_file,msgreceived,fest,nutc,t0)
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niterations=0
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ndither=0
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i1hashdec=0
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fest=0.0
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i1Dec8BitBytes=0
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nbadsync1=-1
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nbadsync2=-1
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goto 999
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endif
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@ -140,70 +144,102 @@ subroutine syncmsk144(cdat,npts,pchk_file,msgreceived,fest,nutc,t0)
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! See if we can find "closed brackets" - a pair of peaks that differ by 864, plus or minus
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! This information is not yet used for anything
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do ii=1,5
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do jj=ii+1,5
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if( (ii .ne. jj) .and. (abs( abs(ipeaks(ii)-ipeaks(jj))-864) .le. 5) ) then
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! do ii=1,5
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! do jj=ii+1,5
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! if( (ii .ne. jj) .and. (abs( abs(ipeaks(ii)-ipeaks(jj))-864) .le. 5) ) then
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! write(*,*) "closed brackets: ",ii,jj,ipeaks(ii),ipeaks(jj),abs(ipeaks(ii)-ipeaks(jj))
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endif
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enddo
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enddo
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! endif
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! enddo
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! enddo
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do iav=1,6
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do ipk=1,5
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do id=1,3
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if( id .eq. 1 ) is=0
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if( id .eq. 2 ) is=-1
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if( id .eq. 3 ) is=1
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! we want ic to be the index of the first sample of the message
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ic=ipeaks(ipk)
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! we want ic to be the index of the first sample of the frame
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ic0=ipeaks(ipk)
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if( ic .le. 864 ) ic=ic+864
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if( ic .gt. 2*864 ) ic=ic-864
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! now do fine adjustment of sync index
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! bb is used to place the sampling index at the center of the eye
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! fine adjustment of sync index
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! bb lag used to place the sampling index at the center of the eye
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do i=1,6
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io=i-3
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ill=max(1,ic+io)
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iul=min(ic+io+6+864,npts)
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bb(i) = sum( ( cdat(ic+io:iul-6:6) * conjg( cdat(ic+io+6:iul:6) ) )*2 )
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if( ic0+11+NSPM .le. npts ) then
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bb(i) = sum( ( cdat(ic0+i-1+6:ic0+i-1+6+NSPM:6) * conjg( cdat(ic0+i-1:ic0+i-1+NSPM:6) ) )*2 )
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else
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bb(i) = sum( ( cdat(ic0+i-1+6:npts:6) * conjg( cdat(ic0+i-1:npts-6:6) ) )*2 )
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endif
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enddo
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iloc=maxloc(abs(bb))
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ibb=iloc(1)
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bba=abs(bb(ibb))
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if( ibb .le. 3 ) ibb=ibb-1
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if( ibb .gt. 3 ) ibb=ibb-7
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do id=1,3 ! slicer dither
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if( id .eq. 1 ) is=0
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if( id .eq. 2 ) is=-1
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if( id .eq. 3 ) is=1
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! Adjust frame index to place peak of bb at desired lag
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ic=ic + ibb-2+is
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if( ic .le. 864 ) ic=ic+864
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if( ic .gt. 2*864 ) ic=ic-864
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ic=ic0+ibb+is
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if( ic .lt. 1 ) ic=ic+864
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! Estimate fine frequency error.
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! Should a larger separation be used when frames are averaged?
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cca=sum(cdat(ic:ic+41)*conjg(cb))
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ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
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cfac=ccb*conjg(cca)
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ferr2=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
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if( ic+56*6+41 .le. npts ) then
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ccb=sum(cdat(ic+56*6:ic+56*6+41)*conjg(cb))
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cfac=ccb*conjg(cca)
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ferr2=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
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else
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ccb=sum(cdat(ic-88*6:ic-88*6+41)*conjg(cb))
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cfac=cca*conjg(ccb)
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ferr2=atan2(imag(cfac),real(cfac))/(twopi*88*6*dt)
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endif
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! Final estimate of the carrier frequency - returned to the calling program
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fest=1500+ferr+ferr2
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! Remove fine frequency error
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call tweak1(cdat,npts,-ferr2,cdat2)
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! place the beginning of the central frame at NSPM+1
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cdat2=cshift(cdat2,ic-865)
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! place the beginning of frame at index NSPM+1
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cdat2=cshift(cdat2,ic-(NSPM+1))
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do iav=1,7
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! Try each of the three frames individually, and then
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! do frame averaging on passes 4 and 5
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if( 0 .eq. 1 ) then
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if( iav .eq. 1 ) then
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c=cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 2 ) then
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c=cdat2(2*NSPM+1:npts)
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elseif( iav .eq. 3 ) then
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c=cdat2(1:NSPM)
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elseif( iav .eq. 2 ) then
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c=cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 3 ) then
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c=cdat2(2*NSPM+1:npts)
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elseif( iav .eq. 4 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 5 ) then
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c=cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:npts)
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 6 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 7 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 8 ) then
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c=cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:npts)
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elseif( iav .eq. 9 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:npts)
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endif
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endif
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if( iav .eq. 1 ) then
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c(1:NSPM)=cdat2(NSPM+1:2*NSPM) !avg 1 frame to the right of ic
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elseif( iav .eq. 2 ) then
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c=cdat2(NSPM-431:NSPM+432) !1 frame centered on ic
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c=cshift(c,-432)
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elseif( iav .eq. 3 ) then !1 frame to the left of ic
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c=cdat2(1:NSPM)
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elseif( iav .eq. 4 ) then
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c=cdat2(NSPM+432:NSPM+432+863) !1 frame beginning 36ms to the right of ic
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c=cshift(c,432)
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elseif( iav .eq. 5 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)
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elseif( iav .eq. 6 ) then
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c=cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:npts)
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elseif( iav .eq. 7 ) then
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c=cdat2(1:NSPM)+cdat2(NSPM+1:2*NSPM)+cdat2(2*NSPM+1:npts)
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endif
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@ -214,28 +250,33 @@ subroutine syncmsk144(cdat,npts,pchk_file,msgreceived,fest,nutc,t0)
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ffin=atan2(imag(cfac),real(cfac))/(twopi*56*6*dt)
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phase0=atan2(imag(cca+ccb),real(cca+ccb))
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! Remove the static phase error from the data
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cfac=cmplx(cos(phase0),sin(phase0))
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c=c*conjg(cfac)
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! sample to get softsamples
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do i=1,72
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softbits(2*i-1)=imag(c(1+(i-1)*12))
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softbits(2*i)=real(c(7+(i-1)*12))
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! do i=1,72
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! softbits(2*i-1)=imag(c(1+(i-1)*12))
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! softbits(2*i)=real(c(7+(i-1)*12))
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! enddo
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! matched filter
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softbits(1)=sum(imag(c(1:6))*pp(7:12))+sum(imag(c(864-5:864))*pp(1:6))
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softbits(2)=sum(real(c(1:12))*pp)
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do i=2,72
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softbits(2*i-1)=sum(imag(c(1+(i-1)*12-6:1+(i-1)*12+5))*pp)
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softbits(2*i)=sum(real(c(7+(i-1)*12-6:7+(i-1)*12+5))*pp)
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enddo
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hardbits=0
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do i=1,144
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if( softbits(i) .ge. 0.0 ) then
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hardbits(i)=1
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endif
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enddo
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! calculated the number of sync-word bits that are incorrect
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! don't present to the decoder if there are too many sync-word bit-errors
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nbadsync1=(8-sum(s8*(2*hardbits(1:8)-1)))/2
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nbadsync2=(8-sum(s8*(2*hardbits(57:57+7)-1)))/2
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nbadsync1=(8-sum( (2*hardbits(1:8)-1)*s8 ) )/2
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nbadsync2=(8-sum( (2*hardbits(1+56:8+56)-1)*s8 ) )/2
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nbadsync=nbadsync1+nbadsync2
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if( nbadsync .gt. 6 ) cycle
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if( nbadsync .gt. 4 ) cycle
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! this could be used to count the number of hard errors that were corrected
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hardword(1:48)=hardbits(9:9+47)
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@ -249,8 +290,7 @@ subroutine syncmsk144(cdat,npts,pchk_file,msgreceived,fest,nutc,t0)
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ssig=sqrt(s2av-sav*sav)
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softbits=softbits/ssig
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! sigma=0.65
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sigma=0.70
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sigma=0.65
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lratio(1:48)=softbits(9:9+47)
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lratio(49:128)=softbits(65:65+80-1)
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lratio=exp(2.0*lratio/(sigma*sigma))
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@ -258,7 +298,7 @@ subroutine syncmsk144(cdat,npts,pchk_file,msgreceived,fest,nutc,t0)
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unscrambledsoftbits(1:127:2)=lratio(1:64)
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unscrambledsoftbits(2:128:2)=lratio(65:128)
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max_iterations=10
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max_iterations=20
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max_dither=50
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call ldpc_decode(unscrambledsoftbits, decoded, max_iterations, niterations, max_dither, ndither)
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@ -309,9 +349,9 @@ goto 999
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endif
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999 continue
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! write(78,1001) nutc,t0,iav,ipk,is,fdiff,fest,nbadsync1,nbadsync2, &
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! write(78,1001) nutc,t0,iav,ipk,is,fdiff,fest,ffin,nbadsync1,nbadsync2, &
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! phase0,niterations,ndither,i1hashdec,i1Dec8BitBytes(10),msgreceived
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!1001 format(i6,f8.2,i4,i4,i4,f8.2,f8.2,i4,i4,f8.2,i4,i4,i4,i4,2x,a22)
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!1001 format(i6,f8.2,i4,i4,i4,f8.2,f8.2,f8.2,i4,i4,f8.2,i4,i4,i4,i4,2x,a22)
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return
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end subroutine syncmsk144
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