WSJT-X/lib/ccf2.f90
Joe Taylor 8fb483a200 Merging code for v1.1 back into the main wsjtx branch.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@3462 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2013-07-08 13:17:22 +00:00

46 lines
1.1 KiB
Fortran

subroutine ccf2(ss,nz,nflip,ccfbest,lagpk)
parameter (LAGMAX=60)
! parameter (LAGMAX=200)
real ss(nz)
real ccf(-LAGMAX:LAGMAX)
integer npr(126)
! 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) !Add two half-symbol contributions
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 subroutine ccf2