From a99798fec474ca4b030453dc4284a6c6b68da27c Mon Sep 17 00:00:00 2001
From: Steven Franke <s.j.franke@icloud.com>
Date: Tue, 1 Nov 2022 17:58:36 -0500
Subject: [PATCH] Improve sync for early decodes.

---
 lib/ft8/sync8.f90  | 26 ++++++++++++++++++--------
 lib/ft8_decode.f90 |  6 ++++--
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/lib/ft8/sync8.f90 b/lib/ft8/sync8.f90
index f048eb394..d498e6f4c 100644
--- a/lib/ft8/sync8.f90
+++ b/lib/ft8/sync8.f90
@@ -1,4 +1,4 @@
-subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,   &
+subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,nzhsym,candidate,   &
      ncand,sbase)
 
   include 'ft8_params.f90'
@@ -73,6 +73,10 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,   &
               t0c=t0c + sum(s(i:i+nfos*6:nfos,m+nssy*72))
            endif
         enddo
+        t=ta+tb
+        t0=t0a+t0b
+        t0=(t0-t)/6.0
+        sync_ab=t/t0
         t=ta+tb+tc
         t0=t0a+t0b+t0c
         t0=(t0-t)/6.0
@@ -81,13 +85,20 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,   &
         t0=t0b+t0c
         t0=(t0-t)/6.0
         sync_bc=t/t0
-        sync2d(i,j)=max(sync_abc,sync_bc)
+        if(j.le.-12) then
+           sync2d(i,j)=sync_bc
+        elseif(j.gt.-12 .and. j.lt. 49) then
+           if(nzhsym.eq.41) sync2d(i,j)=sync_ab
+           if(nzhsym.eq.50) sync2d(i,j)=max(sync_abc,sync_bc)
+        elseif(j.ge.49) then
+           sync2d(i,j)=sync_ab
+        endif
      enddo
   enddo
 
   red=0.
   red2=0.
-  mlag=20
+  mlag=10
   mlag2=JZ
   do i=ia,ib
      ii=maxloc(sync2d(i,-mlag:mlag)) - 1 - mlag 
@@ -110,12 +121,11 @@ subroutine sync8(dd,nfa,nfb,syncmin,nfqso,maxcand,s,candidate,   &
   base=red(ibase)
   red=red/base
   call indexx(red2(ia:ib),iz,indx2)
-  ibase=indx2(npctile) - 1 + ia
-  if(ibase.lt.1) ibase=1
-  if(ibase.gt.nh1) ibase=nh1
-  base2=red2(ibase)
+  ibase2=indx2(npctile) - 1 + ia
+  if(ibase2.lt.1) ibase2=1
+  if(ibase2.gt.nh1) ibase2=nh1
+  base2=red2(ibase2)
   red2=red2/base2
-
   do i=1,min(MAXPRECAND,iz)
      n=ia + indx(iz+1-i) - 1
      if(k.ge.MAXPRECAND) exit
diff --git a/lib/ft8_decode.f90 b/lib/ft8_decode.f90
index 9804a6aea..755157d7c 100644
--- a/lib/ft8_decode.f90
+++ b/lib/ft8_decode.f90
@@ -166,11 +166,13 @@ contains
 ! ndepth=2: subtraction, 3 passes, bp+osd (no subtract refinement) 
 ! ndepth=3: subtraction, 3 passes, bp+osd
     npass=3
-    if(ndepth.eq.1) npass=1
+    if(ndepth.eq.1) npass=2
     do ipass=1,npass
       newdat=.true.
       syncmin=1.3
       if(ndepth.le.2) syncmin=1.6
+!      if(nzhsym.eq.41.or.ipass.eq.1) syncmin=2.0
+      if(nzhsym.eq.41) syncmin=2.0
       if(ipass.eq.1) then
         lsubtract=.true.
         ndeep=ndepth
@@ -187,7 +189,7 @@ contains
       endif 
       call timer('sync8   ',0)
       maxc=MAXCAND
-      call sync8(dd,ifa,ifb,syncmin,nfqso,maxc,s,candidate,   &
+      call sync8(dd,ifa,ifb,syncmin,nfqso,maxc,nzhsym,candidate,   &
            ncand,sbase)
       call timer('sync8   ',1)
       do icand=1,ncand