From 786dc05dcee15bb15b2807259ea87c081da26d91 Mon Sep 17 00:00:00 2001
From: Joe Taylor <k1jt@arrl.org>
Date: Fri, 7 Oct 2016 15:34:55 +0000
Subject: [PATCH] Maintain approximately constant baseline level when degrading
 S/N for tests.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7158 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 lib/degrade_snr.f90 | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/lib/degrade_snr.f90 b/lib/degrade_snr.f90
index b6cbf786d..f2094d827 100644
--- a/lib/degrade_snr.f90
+++ b/lib/degrade_snr.f90
@@ -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