From 87b97039b69aff12517aabca4200133fb053da16 Mon Sep 17 00:00:00 2001
From: Steve Franke <s.j.franke@icloud.com>
Date: Thu, 25 Oct 2018 16:39:17 -0500
Subject: [PATCH] Remove a small bias in Watterson channel simulator channel
 amplitude.

---
 lib/fsk4hf/wsprsimf.f90 | 2 +-
 lib/ft8/ft8sim.f90      | 2 +-
 lib/ft8/watterson.f90   | 9 ++++++---
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/lib/fsk4hf/wsprsimf.f90 b/lib/fsk4hf/wsprsimf.f90
index c6c71fe6e..d6ee25d44 100644
--- a/lib/fsk4hf/wsprsimf.f90
+++ b/lib/fsk4hf/wsprsimf.f90
@@ -77,7 +77,7 @@ program wsprsim
      c=c0
      if(nwav.eq.0) then
         if( fspread .ne. 0.0 .or. delay .ne. 0.0 ) then
-           call watterson(c,NMAX/NDOWN,fs,delay,fspread)
+           call watterson(c,NMAX/NDOWN,NN*NSPS,fs,delay,fspread)
         endif
         c=c*sig
         if(snrdb.lt.90) then
diff --git a/lib/ft8/ft8sim.f90 b/lib/ft8/ft8sim.f90
index 84884c5e2..80f98fcfb 100644
--- a/lib/ft8/ft8sim.f90
+++ b/lib/ft8/ft8sim.f90
@@ -102,7 +102,7 @@ program ft8sim
            phi=mod(phi+dphi,twopi)
         enddo
      enddo
-     if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c0,NMAX,fs,delay,fspread)
+     if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c0,NMAX,NWAVE,fs,delay,fspread)
      c=sig*c0
   
      ib=k
diff --git a/lib/ft8/watterson.f90 b/lib/ft8/watterson.f90
index d047a26eb..a1131d7b1 100644
--- a/lib/ft8/watterson.f90
+++ b/lib/ft8/watterson.f90
@@ -1,5 +1,8 @@
-subroutine watterson(c,npts,fs,delay,fspread)
-
+subroutine watterson(c,npts,nsig,fs,delay,fspread)
+!
+! npts is the total length of the simulated data vector
+! nsig is the number of points that are occupied by signal
+!
   complex c(0:npts-1)
   complex c2(0:npts-1)
   complex cs1(0:npts-1)
@@ -55,7 +58,7 @@ subroutine watterson(c,npts,fs,delay,fspread)
 !     write(61,3001) i/12000.0,c(i)
 !3001 format(3f12.6)
   enddo
-  rms=sqrt(sq/npts)
+  rms=sqrt(sq/nsig) 
   c=c/rms
 
   return