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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6167 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
21 lines
382 B
Fortran
21 lines
382 B
Fortran
subroutine degrade_snr(d2,npts,db)
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integer*2 d2(npts)
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real dat(60*12000)
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dat(1:npts)=d2
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p0=dot_product(dat(1:npts),dat(1:npts))/npts
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s=sqrt(p0*(10.0**(0.1*db) - 1.0))
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do i=1,npts
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d2(i)=nint(dat(i) + s*gran())
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enddo
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! dat(1:npts)=d2
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! p1=dot_product(dat(1:npts),dat(1:npts))/npts
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! print*,db,p0,s,10.0*log10(p1/p0)
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return
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end subroutine degrade_snr
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