WSJT-X/lib/sync66a.f90
2020-08-03 16:30:29 -04:00

95 lines
2.3 KiB
Fortran

subroutine sync66a(iwave,nmax,nsps,nfqso,ntol,xdt,f0)
parameter (NSTEP=4) !Quarter-symbol steps
parameter (IZ=1600,JZ=352,NSPSMAX=1920)
integer*2 iwave(0:nmax-1) !Raw data
integer b11(11) !Barker 11 code
integer ijpk(2) !Indices i and j at peak of sync_sig
real s1(IZ,JZ) !Symbol spectra
real x(JZ) !Work array; 2FSK sync modulation
real sync(4*85) !sync vector
real sync_sig(-64:64,-15:15)
complex c0(0:NSPSMAX) !Complex spectrum of symbol
data b11/1,1,1,0,0,0,1,0,0,1,0/ !Barker 11 code
data sync(1)/99.0/
save sync
if(sync(1).eq.99.0) then
sync=0.
do k=1,22
kk=k
if(kk.gt.11) kk=k-11
sync(16*k-15)=2.0*b11(kk) - 1.0
enddo
endif
nfft=2*NSPS
df=12000.0/nfft !3.125 Hz
istep=nsps/NSTEP
fac=1/32767.0
do j=1,JZ !Compute symbol spectra
ia=(j-1)*istep
ib=ia+nsps-1
k=-1
do i=ia,ib,2
xx=iwave(i)
yy=iwave(i+1)
k=k+1
c0(k)=fac*cmplx(xx,yy)
enddo
c0(k+1:nfft/2)=0.
call four2a(c0,nfft,1,-1,0) !r2c FFT
do i=1,IZ
s1(i,j)=real(c0(i))**2 + aimag(c0(i))**2
enddo
enddo
i0=nint(nfqso/df)
call pctile(s1(i0-64:i0+192,1:JZ),129*JZ,40,base)
s1=s1/base
s1max=20.0
! Make this simpler: just add the 22 nonzero values.
do j=1,JZ
x(j)=maxval(s1(i0-64:i0+192,j))
if(x(j).gt.s1max) s1(i0-64:i0+192,j)=s1(i0-64:i0+192,j)*s1max/x(j)
enddo
dt4=nsps/(NSTEP*12000.0)
j0=0.5/dt4
sync_sig=0.
ia=min(64,nint(ntol/df))
do i=-ia,ia
x=s1(i0+2+i,:)-s1(i0+i,:)
do lag=-15,15
do n=1,4*85
j=n+lag+11
if(j.ge.1 .and. j.le.JZ) sync_sig(i,lag)=sync_sig(i,lag) + sync(n)*x(j)
enddo
enddo
enddo
ijpk=maxloc(sync_sig)
ii=ijpk(1)-65
jj=ijpk(2)-16
! Use peakup() here?
f0=nfqso + ii*df
jdt=jj
tsym=nsps/12000.0
xdt=jdt*tsym/4.0
! do i=-64,64
! write(13,3013) nfqso+i*df,sync_sig(i,jj)
!3013 format(2f12.3)
! enddo
! do j=-15,15
! write(14,3014) j,j*dt4,sync_sig(ii,j)
!3014 format(i5,2f12.3)
! enddo
return
end subroutine sync66a