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Maintain approximately constant baseline level when degrading S/N for tests.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7158 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2016-10-07 15:34:55 +00:00
parent b1d53e1fad
commit 786dc05dce
1 changed files with 2 additions and 7 deletions
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9
lib/degrade_snr.f90
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@ -7,15 +7,10 @@ subroutine degrade_snr(d2,npts,db,bw)
p0=dot_product(dat(1:npts),dat(1:npts))/npts
if(bw.gt.0.0) p0=p0*6000.0/bw
s=sqrt(p0*(10.0**(0.1*db) - 1.0))
fac=sqrt(p0/(p0+s*s))
do i=1,npts
d2(i)=nint(dat(i) + s*gran())
d2(i)=nint(fac*(dat(i) + s*gran()))
enddo
! dat(1:npts)=d2
! p1=dot_product(dat(1:npts),dat(1:npts))/npts
! if(bw.gt.0.0) p1=p1*6000.0/bw
! write(*,3001) db,bw,p0,s,10.0*log10(p1/p0)
!3001 format(5f10.3)
return
end subroutine degrade_snr