From 3160e63dc741b3289127690a40be67bf64f83faa Mon Sep 17 00:00:00 2001
From: Joe Taylor <joe@princeton.edu>
Date: Tue, 15 Dec 2020 09:32:24 -0500
Subject: [PATCH] Several minor tweaks to Q65 decoding.

---
 lib/q65_decode.f90        |  2 +-
 lib/qra/q65/q65_loops.f90 |  5 +++--
 lib/spec64.f90            | 19 ++-----------------
 3 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/lib/q65_decode.f90 b/lib/q65_decode.f90
index 0473b7119..6bfd28c27 100644
--- a/lib/q65_decode.f90
+++ b/lib/q65_decode.f90
@@ -143,7 +143,7 @@ contains
             nFadingModel,ndepth,jpk0,xdt,f0,iaptype,apmask,apsymbols, &
             xdt1,f1,snr2,dat4,id2)
        call timer('q65loops',1)
-       snr2=snr2 + db(6912.0/nsps)
+!       snr2=snr2 + db(6912.0/nsps)
        if(id2.gt.0) exit
     enddo
 
diff --git a/lib/qra/q65/q65_loops.f90 b/lib/qra/q65/q65_loops.f90
index b440e076f..0f83d7275 100644
--- a/lib/qra/q65/q65_loops.f90
+++ b/lib/qra/q65/q65_loops.f90
@@ -29,7 +29,7 @@ subroutine q65_loops(c00,npts2,nsps,mode,mode_q65,nsubmode,nFadingModel, &
 
   idfmax=3
   idtmax=3
-  ibwmin=1
+  ibwmin=0
   ibwmax=2
   maxdist=5
   if(iand(ndepth,3).ge.2) then
@@ -70,7 +70,8 @@ subroutine q65_loops(c00,npts2,nsps,mode,mode_q65,nsubmode,nFadingModel, &
            ndist=ndf**2 + ndt**2 + ((nbw-2))**2
            if(ndist.gt.maxdist) cycle
            !              b90=1.728**ibw
-           b90=3.0**nbw
+           b90=3.0**nbw                    !### Mult by ~baud/3.33 ??? ###
+           if(nbw.eq.0) b90=baud
            if(b90.gt.230.0) cycle
            call timer('q65_intr',0)
            b90ts = b90/baud
diff --git a/lib/spec64.f90 b/lib/spec64.f90
index fe518d747..cf43994dc 100644
--- a/lib/spec64.f90
+++ b/lib/spec64.f90
@@ -11,7 +11,6 @@ subroutine spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
   data isync/1,9,12,13,15,22,23,26,27,33,35,38,46,50,55,60,62,66,69,74,76,85/
 
   nfft=nsps
-  fac=1.0/nfft
 
   if(mode.eq.64) then
      do j=1,NN
@@ -19,7 +18,7 @@ subroutine spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
         if(j.ge.33) jj=j+14                     !Skip middle Costas array
         ja=jpk + (jj-1)*nfft
         jb=ja+nfft-1
-        cs(0:nfft-1)=fac*c0(ja:jb)
+        cs(0:nfft-1)=c0(ja:jb)
         call four2a(cs,nfft,1,-1,1)
         do ii=1,LL
            i=ii-65
@@ -38,7 +37,7 @@ subroutine spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
         j=j+1
         ja=(k-1)*nsps + jpk
         jb=ja+nsps-1
-        cs(0:nfft-1)=fac*c0(ja:jb)
+        cs(0:nfft-1)=c0(ja:jb)
         call four2a(cs,nsps,1,-1,1)             !c2c FFT to frequency
         do ii=1,LL
            i=ii-65+mode64      !mode64 = 1 2 4 8 16 for Q65 A B C D E
@@ -64,19 +63,5 @@ subroutine spec64(c0,nsps,mode,mode64,jpk,s3,LL,NN)
      s3(i,1:NN)=s3(i,1:NN)/(xbase(i)+0.001) !Apply frequency equalization
   enddo
 
-!  print*,'a',LL,NN,jpk,mode,mode64
-!  df=6000.0/nfft
-!  do i=1,LL
-!     write(71,3071) i,i-65,i*df,(s3(i,j),j=1,4)
-!3071 format(2i8,f10.3,4e12.3)
-!  enddo
-
-!  do j=1,NN
-!     ipk1=maxloc(s3(1:LL,j))
-!     m=ipk1(1)-65
-!     write(72,3072) j,m,m/2,m/4,m/8,m/16,m/32,m/64
-!3072 format(8i7)
-!  enddo
-
   return
 end subroutine spec64