git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/map65@342 ab8295b8-cf94-4d9e-aec4-7959e3be5d79

2025-10-31 13:10:19 -04:00 · 2007-01-11 21:52:32 +00:00 · 2007-01-11 21:52:32 +00:00 · ad6ea36de7
commit ad6ea36de7
parent 456edb670d
2 changed files with 44 additions and 68 deletions
--- a/ccf1.f
+++ b/ccf1.f
@ -1,68 +0,0 @@
-      subroutine ccf1(cx,cy,n5,nflip,a,ccfmax,dtmax)
-
-      parameter (NMAX=60*96000)          !Approx samples per half symbol
-      complex cx(n5)
-      complex cy(n5)
-      real a(5)
-      complex w,wstep,za,zb,z
-      real ss(2600)
-      complex csx(0:NMAX/64),csy(0:NMAX/64)
-      data twopi/6.283185307/a1,a2,a3/99.,99.,99./
-      save
-
-      if(a(1).ne.a1 .or. a(2).ne.a2 .or. a(3).ne.a3) then
-         a1=a(1)
-         a2=a(2)
-         a3=a(3)
-
-C  Mix and integrate the complex X and Y signals
-         csx(0)=0.
-         csy(0)=0.
-         w=1.0
-         x0=0.5*(n5+1)
-         s=2.0/n5
-         do i=1,n5
-            x=s*(i-x0)
-            if(mod(i,1000).eq.1) then
-               p2=1.5*x*x - 0.5
-!               p3=2.5*(x**3) - 1.5*x
-!               p4=4.375*(x**4) - 3.75*(x**2) + 0.375
-               dphi=(a(1) + x*a(2) + p2*a(3)) * (twopi/1378.125)
-               wstep=cmplx(cos(dphi),sin(dphi))
-            endif
-            w=w*wstep
-            csx(i)=csx(i-1) + w*cx(i)
-            csy(i)=csy(i-1) + w*cy(i)
-         enddo
-      endif
-
-C  Compute 1/2-symbol powers at 1/16-symbol steps.
-      n6=n5/32
-      fac=1.e-4
-      pol=a(4)/57.2957795
-      aa=cos(pol)
-      bb=sin(pol)
-      fsample=1378.125
-      baud=11025.0/4096.0
-      nsph=nint(0.5*fsample/baud)                !Samples per half symbol
-      do i=1,n6
-         j=32*i
-         k=j-nsph
-         ss(i)=0.
-         if(k.ge.1) then
-            za=csx(j)-csx(k)
-            zb=csy(j)-csy(k)
-            z=aa*za + bb*zb
-            ss(i)=fac*(real(z)**2 + aimag(z)**2)
-         endif
-      enddo
-
-      ccfmax=0.
-      call ccf2(ss,n6,nflip,ccf,lagpk)
-      if(ccf.gt.ccfmax) then
-         ccfmax=ccf
-         dtmax=0.5*lagpk*(512.0/11025.0)
-      endif
-
-      return
-      end
--- a/ccf2.f
+++ b/ccf2.f
@ -0,0 +1,44 @@
+      subroutine ccf2(ss,nz,nflip,ccfbest,lagpk)
+
+      parameter (LAGMAX=20)
+      real ss(nz)
+      real ccf(-LAGMAX:LAGMAX)
+      integer npr(126)
+
+C  The JT65 pseudo-random sync pattern:
+      data npr/
+     + 1,0,0,1,1,0,0,0,1,1,1,1,1,1,0,1,0,1,0,0,
+     + 0,1,0,1,1,0,0,1,0,0,0,1,1,1,0,0,1,1,1,1,
+     + 0,1,1,0,1,1,1,1,0,0,0,1,1,0,1,0,1,0,1,1,
+     + 0,0,1,1,0,1,0,1,0,1,0,0,1,0,0,0,0,0,0,1,
+     + 1,0,0,0,0,0,0,0,1,1,0,1,0,0,1,0,1,1,0,1,
+     + 0,1,0,1,0,0,1,1,0,0,1,0,0,1,0,0,0,0,1,1,
+     + 1,1,1,1,1,1/
+      save
+
+      ccfbest=0.
+      lag1=-LAGMAX
+      lag2=LAGMAX
+      do lag=lag1,lag2
+         s0=0.
+         s1=0.
+         do i=1,126
+            j=2*(8*i + 43) + lag
+            if(j.ge.1 .and. j.le.nz-8) then
+               x=ss(j)+ss(j+8)
+               if(npr(i).eq.0) then
+                  s0=s0 + x
+               else
+                  s1=s1 + x
+               endif
+            endif
+         enddo
+         ccf(lag)=nflip*(s1-s0)
+         if(ccf(lag).gt.ccfbest) then
+            ccfbest=ccf(lag)
+            lagpk=lag
+         endif
+      enddo
+
+      return
+      end