Reintegrate merge from wsjtx_exp branch.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6122 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

lib/decode65a.f90

@@ -1,5 +1,5 @@
-subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,sync2,a,dt,    &
-     nbmkv,nhist,decoded)
+subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,ntrials,     &
+     naggressive,ndepth,sync2,a,dt,nsf,nhist,decoded)
 
 ! Apply AFC corrections to a candidate JT65 signal, then decode it.
 
@@ -17,35 +17,23 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,sync2,a,dt,    &
   save
 
 ! Mix sync tone to baseband, low-pass filter, downsample to 1378.125 Hz
-  dt00=dt
   call timer('filbig  ',0)
   call filbig(dd,npts,f0,newdat,cx,n5,sq0)
   call timer('filbig  ',1)
 
 ! NB: cx has sample rate 12000*77125/672000 = 1378.125 Hz
 
-! Find best DF, f1, f2, and DT.  Start by downsampling to 344.53125 Hz
+! Find best DF, drift, curvature, and DT.  Start by downsampling to 344.53125 Hz
   call timer('fil6521 ',0)
-! Add some zeros at start of c5 arrays -- empirical fix for negative DT's
-  nadd=1089
-  c5x(:nadd)=0.
-  call fil6521(cx,n5,c5x(nadd+1),n6)
-  n6=n6+nadd
+  call fil6521(cx,n5,c5x,n6)
   call timer('fil6521 ',1)
 
   fsample=1378.125/4.
-  a(5)=dt00
-  i0=nint((a(5)+0.5)*fsample) - 2 + nadd
-  if(i0.lt.1) then
-     i0=1
-  endif
-  nz=n6+1-i0
 
-! We're looking only at sync tone here... so why not downsample by another
-! factor of 1/8, say?  Should be a significant execution speed-up.
   call timer('afc65b  ',0)
-! Best fit for DF, f1, and f2
-  call afc65b(c5x(i0),nz,fsample,nflip,a,ccfbest,dtbest)
+! Best fit for DF, drift, banana-coefficient, and dt. fsample = 344.53125 S/s
+  dtbest=dt
+  call afc65b(c5x,n6,fsample,nflip,a,ccfbest,dtbest)
   call timer('afc65b  ',1)
 
   sync2=3.7e-4*ccfbest/sq0                    !Constant is empirical 
@@ -53,26 +41,23 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,sync2,a,dt,    &
 ! Apply AFC corrections to the time-domain signal
 ! Now we are back to using the 1378.125 Hz sample rate, enough to 
 ! accommodate the full JT65C bandwidth.
-
+  a(3)=0 
   call timer('twkfreq ',0)
   call twkfreq65(cx,n5,a)
   call timer('twkfreq ',1)
 
-! Compute spectrum for each half symbol.
-! Adding or subtracting a small number (e.g., 5) to j may make it decode.\
-! NB: might want to try computing full-symbol spectra (nfft=512, even for
-! submodes B and C).
-
+! Compute spectrum for each symbol.
   nsym=126
   nfft=512
-  j=(dt00+dtbest+2.685)*1378.125
+  j=int(dtbest*1378.125)
   if(j.lt.0) j=0
 
+  c5a=cmplx(0.0,0.0)
   call timer('sh_ffts ',0)
   do k=1,nsym
      do i=1,nfft
         j=j+1
-        c5a(i)=cx(j)
+        if( j .le. NMAX/8 ) c5a(i)=cx(j)
      enddo
      call four2a(c5a,nfft,1,1,1)
      do i=1,66
@@ -85,8 +70,9 @@ subroutine decode65a(dd,npts,newdat,nqd,f0,nflip,mode65,sync2,a,dt,    &
   call timer('sh_ffts ',1)
 
   call timer('dec65b  ',0)
-  call decode65b(s2,nflip,mode65,nqd,nbmkv,nhist,decoded)
-  dt=dt00 + dtbest + 1.7
+  call decode65b(s2,nflip,mode65,ntrials,naggressive,ndepth,nqd,nsf,   &
+       nhist,decoded)
+  dt=dtbest !return new, improved estimate of dt
   call timer('dec65b  ',1)
 
   return