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