From 9458acb01b1010b868613998d53fd712d020f1f5 Mon Sep 17 00:00:00 2001
From: Joe Taylor <k1jt@arrl.org>
Date: Thu, 18 May 2017 15:59:30 +0000
Subject: [PATCH] Limit WSPR-LF frequency search range to 1600-1650 Hz.  Enable
 S/N degradation.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7689 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 lib/degrade_snr.f90       | 15 ++++++++-----
 lib/fsk4hf/wspr_fsk8d.f90 | 45 +++++++++++++++++++++++----------------
 mainwindow.cpp            |  6 +++---
 3 files changed, 40 insertions(+), 26 deletions(-)

diff --git a/lib/degrade_snr.f90 b/lib/degrade_snr.f90
index d2fedee2f..fd5db5f1b 100644
--- a/lib/degrade_snr.f90
+++ b/lib/degrade_snr.f90
@@ -1,15 +1,20 @@
 subroutine degrade_snr(d2,npts,db,bw)
 
-  integer*2 d2(npts)
-  real dat(60*12000)
+! Degrade S/N by specified number of dB.
 
-  dat(1:npts)=d2
-  p0=dot_product(dat(1:npts),dat(1:npts))/npts
+  integer*2 d2(npts)
+  
+  p0=0.
+  do i=1,npts
+     x=d2(i)
+     p0=p0 + x*x
+  enddo
+  p0=p0/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(fac*(dat(i) + s*gran()))
+     d2(i)=nint(fac*(d2(i) + s*gran()))
   enddo
 
   return
diff --git a/lib/fsk4hf/wspr_fsk8d.f90 b/lib/fsk4hf/wspr_fsk8d.f90
index 923ae9289..235d7278f 100644
--- a/lib/fsk4hf/wspr_fsk8d.f90
+++ b/lib/fsk4hf/wspr_fsk8d.f90
@@ -37,23 +37,24 @@ program wspr_fsk8d
   data icos7/2,5,6,0,4,1,3/             !Costas 7x7 tone pattern
 
   nargs=iargc()
-  if(nargs.lt.2) then
-     print*,'Usage:   wspr_fsk8d [-a <data_dir>] [-f fMHz] file1 [file2 ...]'
+  if(nargs.lt.7) then
+     print*,'Usage:   wspr_fsk8d -d db -a data_dir -f fMHz file1 [file2 ...]'
      go to 999
   endif
-  iarg=1
-  data_dir="."
-  call getarg(iarg,arg)
-  if(arg(1:2).eq.'-a') then
-     call getarg(iarg+1,data_dir)
-     iarg=iarg+2
-  endif
-  call getarg(iarg,arg)
-  if(arg(1:2).eq.'-f') then
-     call getarg(iarg+1,arg)
-     read(arg,*) fMHz
-     iarg=iarg+2
-  endif
+  call getarg(1,arg)
+  if(arg(1:3).ne.'-d ') go to 999
+  call getarg(2,arg)
+  read(arg,*) degrade
+  rxbw=3000.
+
+  call getarg(3,arg)
+  if(arg(1:3).ne.'-f ') go to 999
+  call getarg(4,arg)
+  read(arg,*) fMHz
+
+  call getarg(5,arg)
+  if(arg(1:3).ne.'-a ') go to 999
+  call getarg(6,data_dir)
   
   open(13,file=trim(data_dir)//'/ALL_WSPR.TXT',status='unknown',   &
        position='append')
@@ -77,7 +78,7 @@ program wspr_fsk8d
      enddo
   enddo
 
-  do ifile=iarg,nargs
+  do ifile=7,nargs
      call getarg(ifile,infile)
      open(10,file=infile,status='old',access='stream')
      read(10,end=999) ihdr,iwave
@@ -85,10 +86,13 @@ program wspr_fsk8d
      j2=index(infile,'.wav')
      read(infile(j2-4:j2-1),*) nutc
      datetime=infile(j2-11:j2-1)
+     if(degrade.gt.0.0) call degrade_snr(iwave,NMAX,degrade,rxbw)
      call wspr_fsk8_downsample(iwave,c)
 
      pmax=0.
      df1=fs/(2*N7)
+     ia=nint(100.0/df1)
+     ib=nint(150.0/df1)
      ipk=0
      jpk=0
 ! Get xdt and f0 from the sync arrays
@@ -104,6 +108,9 @@ program wspr_fsk8d
            p=1.e-9*(real(c1(i))**2 + aimag(c1(i))**2 +                        &
                 real(c2(i))**2 + aimag(c2(i))**2)
            ss(i)=p
+        enddo
+        do i=ia,ib
+           p=ss(i)
            if(p.gt.pmax) then
               pmax=p
               ipk=i
@@ -131,7 +138,8 @@ program wspr_fsk8d
      do j=1,ND
         k=j+7
         ps=s(0:7,k)
-!        ps=sqrt(ps)                                !### ??? ###
+        !        ps=sqrt(ps)                                !### ??? ###
+        ps=log(ps)
         r1=max(ps(1),ps(3),ps(5),ps(7))-max(ps(0),ps(2),ps(4),ps(6))
         r2=max(ps(2),ps(3),ps(6),ps(7))-max(ps(0),ps(1),ps(4),ps(5))
         r4=max(ps(4),ps(5),ps(6),ps(7))-max(ps(0),ps(1),ps(2),ps(3))
@@ -155,7 +163,8 @@ program wspr_fsk8d
      if(niterations.ge.0) call chkcrc10(decoded,nbadcrc)
      if(niterations.lt.0 .or. nbadcrc.ne.0) ifer=1
      nsnr=nint(xsnr)
-     freq=fMHz + 1.d-6*f0
+!     freq=fMHz + 1.d-6*f0
+     freq=1.d-6*(f0+1500)
      nfdot=0
      message='                      '
      if(ifer.eq.0) then
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 40447c022..6a414ab3d 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -1288,7 +1288,9 @@ void MainWindow::dataSink(qint64 frames)
       QString t3=cmnd;
       int i1=cmnd.indexOf("/wsprd ");
       cmnd=t3.mid(0,i1+7) + t3.mid(i1+7);
-      if(m_mode=="WSPR-LF") cmnd=cmnd.replace("/wsprd ","/wspr_fsk8d ");
+      QString degrade;
+      degrade.sprintf("-d %4.1f ",m_config.degrade());
+      if(m_mode=="WSPR-LF") cmnd=cmnd.replace("/wsprd ","/wspr_fsk8d "+degrade+t2);
       if (ui) ui->DecodeButton->setChecked (true);
       m_cmndP1=QDir::toNativeSeparators(cmnd);
       p1Timer.start(1000);
@@ -2226,7 +2228,6 @@ void MainWindow::diskDat()                                   //diskDat()
     float db=m_config.degrade();
     float bw=m_config.RxBandwidth();
     if(db > 0.0) degrade_snr_(dec_data.d2,&dec_data.params.kin,&db,&bw);
-
     for(int n=1; n<=m_hsymStop; n++) {                      // Do the waterfall spectra
       k=(n+1)*kstep;
       if(k > dec_data.params.kin) break;
@@ -5403,7 +5404,6 @@ void MainWindow::transmit (double snr)
                         m_TRperiod);
   }
   if (m_mode=="WSPR-LF") {
-    qDebug() << "a" << m_toneSpacing;
     Q_EMIT sendMessage (NUM_WSPR_LF_SYMBOLS, 24576.0,
                         ui->TxFreqSpinBox->value(),
                         m_toneSpacing, m_soundOutput,