From df69562a9fc1cb7e75354684f8f24feff68e91ce Mon Sep 17 00:00:00 2001
From: Joe Taylor <joe@princeton.edu>
Date: Mon, 19 Oct 2020 15:24:32 -0400
Subject: [PATCH] More tweaks to QRA65 decoder.

---
 lib/qra65_decode.f90 | 32 +++++++++++++++-----------------
 lib/qra_loops.f90    |  9 ++++++---
 lib/sync_qra65.f90   | 17 ++++++++++++++++-
 3 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/lib/qra65_decode.f90 b/lib/qra65_decode.f90
index beb174527..e7ff43626 100644
--- a/lib/qra65_decode.f90
+++ b/lib/qra65_decode.f90
@@ -118,21 +118,20 @@ contains
     call sync_qra65(iwave,ntrperiod*12000,mode65,nsps,nfqso,ntol,xdt,f0,snr1)
     call timer('sync_q65',1)
 
-    jpk0=(xdt+1.0)*6000   !###
-    if(jpk0.lt.0) jpk0=0
-
-    fac=1.0/32767.0
-    dd=fac*iwave
-    nmode=65
-
-    call ana64(dd,npts,c00)
-
-    call timer('qraloops',0)
-    call qra_loops(c00,npts/2,nmode,mode65,nsubmode,nFadingModel,       &
-         ndepth,nc1,nc2,ng2,naptype,jpk0,xdt,f0,width,snr2,irc,dat4)
-    call timer('qraloops',1)
-    xdt=xdt+0.4        !### Empirical -- WHY ??? ###
-    snr2=snr2 + db(6912.0/nsps)
+    irc=-1
+    if(snr1.ge.2.7) then
+       jpk0=(xdt+1.0)*6000   !###
+       if(jpk0.lt.0) jpk0=0
+       fac=1.0/32767.0
+       dd=fac*iwave
+       nmode=65
+       call ana64(dd,npts,c00)
+       call timer('qraloops',0)
+       call qra_loops(c00,npts/2,nmode,mode65,nsubmode,nFadingModel,       &
+            ndepth,nc1,nc2,ng2,naptype,jpk0,xdt,f0,width,snr2,irc,dat4)
+       call timer('qraloops',1)
+       snr2=snr2 + db(6912.0/nsps)
+    endif
     decoded='                                     '
     if(irc.ge.0) then
        call unpackmsg(dat4,decoded)               !Unpack the user message
@@ -146,8 +145,7 @@ contains
        call this%callback(nutc,sync,nsnr,xdt,f0,decoded,              &
             irc,qual,ntrperiod,fmid,w50)
     else
-       snr2=0.
-       nsnr=-30 
+       nsnr=db(snr1) - 32.0
 !### TEMPORARY? ###       
        call this%callback(nutc,sync,nsnr,xdt,f0,decoded,              &
             irc,qual,ntrperiod,fmid,w50)
diff --git a/lib/qra_loops.f90 b/lib/qra_loops.f90
index 73eeb20f7..f2d1e30e5 100644
--- a/lib/qra_loops.f90
+++ b/lib/qra_loops.f90
@@ -31,17 +31,19 @@ subroutine qra_loops(c00,npts2,mode,mode64,nsubmode,nFadingModel,      &
   if(ndepth.eq.3) maxdist=30
 
   do idf=1,idfmax
-     ndf=idfn/2
+     ndf=idf/2
      if(mod(idf,2).eq.0) ndf=-ndf
      a=0.
-     a(1)=-(f0+0.868*ndf)
+     a(1)=-(f0+0.4*ndf)
      call twkfreq(c00,c0,npts2,6000.0,a)
      do idt=1,idtmax
         ndt=idt/2
         if(mod(idt,2).eq.0) ndt=-ndt
         jpk=jpk0 + 240*ndt                  !240/6000 = 0.04 s = tsym/32
         if(jpk.lt.0) jpk=0
+        call timer('spec64  ',0)
         call spec64(c0,nsps,mode,jpk,s3,LL,NN)
+        call timer('spec64  ',1)
         call pctile(s3,LL*NN,40,base)
         s3=s3/base
         where(s3(1:LL*NN)>s3lim) s3(1:LL*NN)=s3lim
@@ -91,7 +93,8 @@ subroutine qra_loops(c00,npts2,mode,mode64,nsubmode,nFadingModel,      &
      ndist=ndistx
   endif
 
-200 continue
+200 if(mode.eq.65) xdt=xdt+0.4        !### Empirical -- WHY ??? ###
+
 !### For tests only:
   if(irc.ge.0) then
      open(53,file='fort.53',status='unknown',position='append')
diff --git a/lib/sync_qra65.f90 b/lib/sync_qra65.f90
index b18aa8870..401efcc3c 100644
--- a/lib/sync_qra65.f90
+++ b/lib/sync_qra65.f90
@@ -97,7 +97,22 @@ subroutine sync_qra65(iwave,nmax,mode65,nsps,nfqso,ntol,xdt,f0,snr1)
   jpk=ijpk(2)-27
   f0=nfqso + ipk*df
   xdt=jpk*dtstep
-  snr1=maxval(ccf)/22.0
 
+  sq=0.
+  nsq=0
+  do j=lag1,lag2
+     if(abs(j-jpk).gt.6) then
+        sq=sq + ccf(ipk,j)**2
+        nsq=nsq+1
+     endif
+  enddo
+  rms=sqrt(sq/nsq)
+  snr1=ccf(ipk,jpk)/rms
+
+!  do j=lag1,lag2
+!     write(55,3055) j,j*dtstep,ccf(ipk,j)/rms
+!3055 format(i5,f8.3,f10.3)
+!  enddo
+  
   return
 end subroutine sync_qra65