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https://github.com/saitohirga/WSJT-X.git
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c75c4aefda
Better AFC (wider range of possible drifts; more accurate DT alignment). Better definition of metric tables used by Fano decoder. Zero-centeres soft symbols, instead of offset +128. Tuned several empirical parameters. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5004 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
89 lines
2.3 KiB
Fortran
89 lines
2.3 KiB
Fortran
subroutine symspec2(c5,nz3,nsps8,nspsd,fsample,freq,drift,snrdb,schk, &
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i1SoftSymbolsScrambled)
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! Compute soft symbols from the final downsampled data
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complex c5(0:4096-1)
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complex z
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integer*1 i1SoftSymbolsScrambled(207)
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real aa(3)
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real ss2(0:8,85)
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real ss3(0:7,69)
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include 'jt9sync.f90'
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data scale/10.0/
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aa(1)=-1500.0/nsps8
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aa(2)=0.
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aa(3)=0.
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do i=0,8 !Loop over the 9 tones
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if(i.ge.1) call twkfreq(c5,c5,nz3,fsample,aa)
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m=0
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k=-1
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do j=1,85 !Loop over all symbols
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z=0.
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do n=1,nspsd !Sum over 16 samples
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k=k+1
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z=z+c5(k)
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enddo
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ss2(i,j)=real(z)**2 + aimag(z)**2 !Symbol speactra, data and sync
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if(i.ge.1 .and. isync(j).eq.0) then
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m=m+1
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ss3(i-1,m)=ss2(i,j) !Symbol speactra, data only
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endif
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enddo
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enddo
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call chkss2(ss2,freq,drift,schk)
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ss=0.
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sig=0.
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do j=1,69
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smax=0.
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do i=0,7
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smax=max(smax,ss3(i,j))
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ss=ss+ss3(i,j)
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enddo
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sig=sig+smax
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ss=ss-smax
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enddo
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ave=ss/(69*7) !Baseline
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call pctile(ss2,9*85,35,xmed)
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ss3=ss3/ave
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sig=sig/69. !Signal
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t=max(1.0,sig - 1.0)
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snrdb=db(t) - 61.3
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m0=3
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k=0
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do j=1,69
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smax=0.
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do i=0,7
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if(ss3(i,j).gt.smax) smax=ss3(i,j)
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enddo
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do m=m0-1,0,-1 !Get bit-wise soft symbols
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if(m.eq.2) then
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r1=max(ss3(4,j),ss3(5,j),ss3(6,j),ss3(7,j))
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r0=max(ss3(0,j),ss3(1,j),ss3(2,j),ss3(3,j))
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else if(m.eq.1) then
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r1=max(ss3(2,j),ss3(3,j),ss3(4,j),ss3(5,j))
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r0=max(ss3(0,j),ss3(1,j),ss3(6,j),ss3(7,j))
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else
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r1=max(ss3(1,j),ss3(2,j),ss3(4,j),ss3(7,j))
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r0=max(ss3(0,j),ss3(3,j),ss3(5,j),ss3(6,j))
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endif
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k=k+1
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i4=nint(scale*(r1-r0))
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if(i4.lt.-127) i4=-127
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if(i4.gt.127) i4=127
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! i4=i4+128
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! if(i4.le.127) i1SoftSymbolsScrambled(k)=i4
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! if(i4.ge.128) i1SoftSymbolsScrambled(k)=i4-256
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i1SoftSymbolsScrambled(k)=i4
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enddo
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enddo
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return
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end subroutine symspec2
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