mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-15 08:31:57 -05:00
a51c5c4251
As at ^/branches/wsjtx_exp@5271 git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@5272 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
50 lines
1.3 KiB
Fortran
50 lines
1.3 KiB
Fortran
subroutine xcor4(s2,ipk,nsteps,nsym,ich,mode4)
|
|
|
|
! Computes ccf of the 4-FSK spectral array s2 and the pseudo-random
|
|
! array pr2. Returns peak of CCF and the lag at which peak occurs.
|
|
! The CCF peak may be either positive or negative, with negative
|
|
! implying a message with report.
|
|
|
|
use jt4
|
|
parameter (NHMAX=1260) !Max length of power spectra
|
|
parameter (NSMAX=525) !Max number of half-symbol steps
|
|
real s2(NHMAX,NSMAX) !2d spectrum, stepped by half-symbols
|
|
real a(NSMAX)
|
|
save
|
|
|
|
nw=nch(ich)
|
|
do j=1,nsteps
|
|
n=2*mode4
|
|
if(mode4.eq.1) then
|
|
a(j)=max(s2(ipk+n,j),s2(ipk+3*n,j)) - max(s2(ipk ,j),s2(ipk+2*n,j))
|
|
else
|
|
kz=max(1,nw/2)
|
|
ss0=0.
|
|
ss1=0.
|
|
ss2=0.
|
|
ss3=0.
|
|
wsum=0.
|
|
do k=-kz+1,kz-1
|
|
w=float(kz-iabs(k))/nw
|
|
wsum=wsum+w
|
|
ss0=ss0 + w*s2(ipk +k,j)
|
|
ss1=ss1 + w*s2(ipk+ n+k,j)
|
|
ss2=ss2 + w*s2(ipk+2*n+k,j)
|
|
ss3=ss3 + w*s2(ipk+3*n+k,j)
|
|
enddo
|
|
a(j)=(max(ss1,ss3) - max(ss0,ss2))/sqrt(wsum)
|
|
endif
|
|
enddo
|
|
|
|
do lag=1,65
|
|
x=0.
|
|
do i=1,nsym
|
|
j=2*i-1+lag
|
|
if(j.ge.1 .and. j.le.nsteps) x=x+a(j)*float(2*npr(i)-1)
|
|
enddo
|
|
zz(ipk,lag,ich)=x
|
|
enddo
|
|
|
|
return
|
|
end subroutine xcor4
|