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https://github.com/saitohirga/WSJT-X.git
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335536b6ec
Better calc of snrdb, especially for strong signals. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2719 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
123 lines
2.7 KiB
Fortran
123 lines
2.7 KiB
Fortran
subroutine spec9(c0,npts8,nsps,fpk0,fpk,xdt,snrdb,i1SoftSymbols)
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parameter (MAXFFT=31500)
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complex c0(0:npts8-1)
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complex c1(0:2700000)
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real*4 ssym(0:7,69)
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real*4 sx(0:31500-1)
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complex c(0:MAXFFT-1)
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integer*1 i1SoftSymbolsScrambled(207)
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integer*1 i1SoftSymbols(207)
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integer*1 i1
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integer ig(0:7)
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equivalence (i1,i4)
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data ig/0,1,3,2,7,6,4,5/ !Gray code removal
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include 'jt9sync.f90'
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save
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! Fix up the data in c0()
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sum=0.
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do i=0,npts8-1
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sum=sum + real(c0(i))**2 + aimag(c0(i))**2
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enddo
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rms=sqrt(sum/npts8)
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fac=1.0/rms
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twopi=8.0*atan(1.0)
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phi=0.
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dphi=twopi*500.0/1500.0
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do i=0,npts8-1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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if(phi.lt.-twopi) phi=phi+twopi
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c1(i)=fac*cmplx(aimag(c0(i)),real(c0(i)))*cmplx(cos(phi),sin(phi))
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enddo
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nsps8=nsps/8
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foffset=fpk0
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istart=1520
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call peakdf9(c1,npts8,nsps8,istart,foffset,idf)
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fpk=fpk0 + idf*0.1*1500.0/nsps8
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foffset=foffset + idf*0.1*1500.0/nsps8
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call peakdt9(c1,npts8,nsps8,istart,foffset,idt)
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istart=istart + 0.0625*nsps8*idt
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xdt=istart/1500.0 - 1.0
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fshift=foffset
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twopi=8.0*atan(1.0)
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dphi=twopi*fshift/1500.0
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nfft=nsps8
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nsym=min((npts8-istart)/nsps8,85)
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k=0
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do j=1,nsym
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if(isync(j).eq.1) cycle
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k=k+1
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ia=(j-1)*nsps8 + istart
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ib=ia+nsps8-1
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c(0:nfft-1)=c1(ia:ib)
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phi=0.
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do i=0,nfft-1
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phi=phi + dphi
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c(i)=c(i) * cmplx(cos(phi),-sin(phi))
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enddo
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call four2a(c,nfft,1,-1,1)
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do i=0,nfft-1
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sx(i)=real(c(i))**2 + aimag(c(i))**2
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if(i.ge.1 .and. i.le.8) ssym(ig(i-1),k)=sx(i)
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enddo
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enddo
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sum=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,ssym(i,j))
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sum=sum+ssym(i,j)
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enddo
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sig=sig+smax
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sum=sum-smax
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enddo
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ave=sum/(69*7)
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call pctile(sx,nsps8,50,xmed)
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ssym=ssym/ave
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sig=sig/69.
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df8=1500.0/nsps8
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t=max(1.0,sig/xmed - 1.0)
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snrdb=db(t) - db(2500.0/df8) - 5.0
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m0=3
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ntones=8
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k=0
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do j=1,69
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do m=m0-1,0,-1 !Get bit-wise soft symbols
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n=2**m
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r1=0.
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r2=0.
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do i=0,ntones-1
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if(iand(i,n).ne.0) then
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r1=max(r1,ssym(i,j))
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else
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r2=max(r2,ssym(i,j))
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endif
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enddo
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k=k+1
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i4=nint(10.0*(r1-r2))
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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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i1SoftSymbolsScrambled(k)=i1
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enddo
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enddo
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call interleave9(i1SoftSymbolsScrambled,-1,i1SoftSymbols)
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call flush(81)
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call flush(82)
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return
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end subroutine spec9
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