From 5b0975bf45c2a3777323c1dcb0e9e15bcf7688c3 Mon Sep 17 00:00:00 2001
From: Joe Taylor <joe@princeton.edu>
Date: Thu, 7 Jan 2021 11:13:43 -0500
Subject: [PATCH] Correct several flaws in message averaging.  Still may want
 to handle MAXAVE better?

---
 lib/q65_decode.f90       |  3 ++-
 lib/qra/q65/q65_avg.f90  | 28 +++++++++++++++-------------
 lib/qra/q65/q65_sync.f90 |  2 +-
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/lib/q65_decode.f90 b/lib/q65_decode.f90
index 6068e3ef3..896a52ac7 100644
--- a/lib/q65_decode.f90
+++ b/lib/q65_decode.f90
@@ -157,8 +157,9 @@ contains
        if(idec.gt.0) go to 100       !Successful decode, we're done
     enddo
 
-! No single-transmission decode.
+! There was no single-transmission decode.
     if(iand(ndepth,16).eq.16) then
+! Try for an average decode.
        call q65_avg2(ntrperiod,ntol,baud,nsubmode,nQSOprogress,lapcqonly, &
             ibwa,ibwb,codewords,ncw,xdt,f0,snr1,snr2,dat4,idec)
     endif
diff --git a/lib/qra/q65/q65_avg.f90 b/lib/qra/q65/q65_avg.f90
index a1f748792..d6dd07de2 100644
--- a/lib/qra/q65/q65_avg.f90
+++ b/lib/qra/q65/q65_avg.f90
@@ -11,7 +11,6 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
   character*1 cused(MAXAVE)
   character*6 cutc
   real s3(-64:LL-65,63)                  !Symbol spectra
-  integer iused(MAXAVE)
   integer dat4(13)
   integer codewords(63,206)
   integer apmask1(78),apsymbols1(78)
@@ -19,13 +18,8 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
   data first/.true./
   save
 
-  if(first .or. LL.ne.LL0 .or.lclearave) then
-     iutc=-1
-     iseq=-1
-     f0save=0.0
-     nsave=0
+  if(LL.ne.LL0) then
      LL0=LL
-     first=.false.
      if(allocated(s3save)) deallocate(s3save)
      if(allocated(s3avg)) deallocate(s3avg)
      allocate(s3save(-64:LL-65,63,MAXAVE))
@@ -33,6 +27,15 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
      s3save=0.
      s3avg=0.
   endif
+  if(first .or. lclearave) then
+     iutc=-1
+     iseq=-1
+     f0save=0.0
+     nsave=0
+     first=.false.
+     s3save=0.
+     s3avg=0.
+  endif
 
   if(ntrperiod.eq.15) then
      dtdiff=0.038
@@ -52,7 +55,7 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
 
 ! Save data for message averaging
   nsave=nsave+1
-  nsave=mod(nsave-1,MAXAVE)+1
+  if(nsave.gt.MAXAVE) nsave=nsave-MAXAVE
   n=nutc
   if(ntrperiod.ge.60) n=100*n
   write(cutc,'(i6.6)') n
@@ -62,7 +65,7 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
   iutc(nsave)=nutc                          !UTC, hhmm or hhmmss
   snr1save(nsave)=snr1                      !SNR from sync
   xdtsave(nsave)=xdt                        !DT
-  f0save(nsave)=f0                           !f0
+  f0save(nsave)=f0                          !f0
   s3save(:,:,nsave)=s3(:,:)                 !Symbol spectra
 
 10 return
@@ -93,9 +96,7 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
      xdtsum=xdtsum + xdtsave(i)
      fsum=fsum + f0save(i)
      navg=navg+1
-     iused(navg)=i
   enddo
-  if(navg.lt.MAXAVE) iused(navg+1)=0
   
 ! Find averages of snr1, xdt, and f0 used in this decoding attempt.
   snr1ave=0.
@@ -108,7 +109,8 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
   endif
 
 ! Write parameters for display to User in the Message Averaging (F7) window.
-  do i=1,nsave
+  do i=1,MAXAVE
+     if(iutc(i).lt.0) cycle
      if(ntrperiod.le.30) write(14,1000) cused(i),iutc(i),snr1save(i),    &
           xdtsave(i),f0save(i)
 1000 format(a1,i7.6,f6.1,f6.2,f7.1)
@@ -183,7 +185,7 @@ subroutine q65_avg(nutc,ntrperiod,LL,nfqso,ntol,lclearave,xdt,f0,snr1,s3)
 100 return
 
   entry q65_clravg
-  
+
   iutc=-1
   iseq=-1
   snr1save=0.
diff --git a/lib/qra/q65/q65_sync.f90 b/lib/qra/q65/q65_sync.f90
index ee0e28794..ed718a664 100644
--- a/lib/qra/q65/q65_sync.f90
+++ b/lib/qra/q65/q65_sync.f90
@@ -60,7 +60,7 @@ subroutine q65_sync(nutc,iwave,ntrperiod,mode_q65,codewords,ncw,nsps,   &
   allocate(ccf(-ia2:ia2,-53:214))
   allocate(ccf1(-ia2:ia2))
   allocate(ccf2(-ia2:ia2))
-  
+  s3=0.
   if(sync(1).eq.99.0) then               !Generate the sync vector
      sync=-22.0/63.0                     !Sync tone OFF  
      do k=1,22