mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-22 20:28:42 -05:00
50 lines
1.4 KiB
Fortran
50 lines
1.4 KiB
Fortran
subroutine sync4d(cd0,i0,ctwk,itwk,sync)
|
|
|
|
! Compute sync power for a complex, downsampled FT4 signal.
|
|
|
|
include 'ft4_params.f90'
|
|
parameter(NP=NMAX/NDOWN,NSS=NSPS/NDOWN)
|
|
complex cd0(0:NP-1)
|
|
complex csync(4*NSS)
|
|
complex csync2(4*NSS)
|
|
complex ctwk(4*NSS)
|
|
complex z1,z2,z3,z4
|
|
logical first
|
|
integer icos4(0:3)
|
|
data icos4/0,1,3,2/
|
|
data first/.true./
|
|
save first,twopi,csync
|
|
|
|
p(z1)=real(z1)**2 + aimag(z1)**2 !Statement function for power
|
|
|
|
if( first ) then
|
|
twopi=8.0*atan(1.0)
|
|
k=1
|
|
phi=0.0
|
|
do i=0,3
|
|
dphi=twopi*icos4(i)/real(NSS)
|
|
do j=1,NSS
|
|
csync(k)=cmplx(cos(phi),sin(phi))
|
|
phi=mod(phi+dphi,twopi)
|
|
k=k+1
|
|
enddo
|
|
enddo
|
|
first=.false.
|
|
endif
|
|
|
|
sync=0
|
|
i1=i0 !four Costas arrays
|
|
i2=i0+33*NSS-1
|
|
i3=i0+66*NSS-1
|
|
i4=i0+99*NSS-1
|
|
csync2=csync
|
|
if(itwk.eq.1) csync2=ctwk*csync2 !Tweak the frequency
|
|
if(i1.ge.0 .and. i1+4*NSS-1.le.NP-1) z1=sum(cd0(i1:i1+4*NSS-1)*conjg(csync2))
|
|
if(i2.ge.0 .and. i2+4*NSS-1.le.NP-1) z2=sum(cd0(i2:i2+4*NSS-1)*conjg(csync2))
|
|
if(i3.ge.0 .and. i3+4*NSS-1.le.NP-1) z3=sum(cd0(i3:i3+4*NSS-1)*conjg(csync2))
|
|
if(i4.ge.0 .and. i4+4*NSS-1.le.NP-1) z4=sum(cd0(i4:i4+4*NSS-1)*conjg(csync2))
|
|
sync = sync + p(z1) + p(z2) + p(z3) + p(z4)
|
|
|
|
return
|
|
end subroutine sync4d
|