subroutine sync8(dd,nfa,nfb,nfqso,s,candidate,ncand) include 'ft8_params.f90' parameter (JZ=31) !DT up to +/- 2.5 s complex cx(0:NH1) real s(NH1,NHSYM) real savg(NH1) real x(NFFT1) real sync2d(NH1,-JZ:JZ) real red(NH1) real candidate0(3,200) real candidate(3,200) real dd(NMAX) integer jpeak(NH1) integer indx(NH1) integer ii(1) integer icos7(0:6) data icos7/2,5,6,0,4,1,3/ !Costas 7x7 tone pattern equivalence (x,cx) ! Compute symbol spectra at half-symbol steps. savg=0. istep=NSPS/2 !960 tstep=istep/12000.0 !0.08 s df=12000.0/NFFT1 !3.125 Hz ! Compute symbol spectra at half-symbol steps fac=1.0/300.0 do j=1,NHSYM ia=(j-1)*istep + 1 ib=ia+NSPS-1 x(1:NSPS)=fac*dd(ia:ib) x(NSPS+1:)=0. call four2a(x,NFFT1,1,-1,0) !r2c FFT do i=1,NH1 s(i,j)=real(cx(i))**2 + aimag(cx(i))**2 enddo savg=savg + s(1:NH1,j) !Average spectrum enddo savg=savg/NHSYM ! do i=1,NH1 ! write(51,3051) i*df,savg(i),db(savg(i)) !3051 format(f10.3,e12.3,f12.3) ! enddo ia=max(1,nint(nfa/df)) ib=nint(nfb/df) do i=ia,ib do j=-JZ,JZ t=0. t0=0. do n=0,6 k=j+2*n if(k.ge.1) then t=t + s(i+2*icos7(n),k) t0=t0 + sum(s(i:i+12:2,k)) endif t=t + s(i+2*icos7(n),k+72) t0=t0 + sum(s(i:i+12:2,k+72)) if(k+144.le.NHSYM) then t=t + s(i+2*icos7(n),k+144) t0=t0 + sum(s(i:i+12:2,k+144)) endif enddo t0=(t0-t)/6.0 sync2d(i,j)=t/t0 enddo enddo red=0. do i=ia,ib ii=maxloc(sync2d(i,-JZ:JZ)) - 1 - JZ j0=ii(1) jpeak(i)=j0 red(i)=sync2d(i,j0) ! write(52,3052) i*df,red(i),db(red(i)) !3052 format(3f12.3) enddo iz=ib-ia+1 call indexx(red(ia:ib),iz,indx) ibase=indx(nint(0.40*iz)) - 1 + ia base=red(ibase) red=red/base candidate0=0. k=0 syncmin=2.0 do i=1,100 n=ia + indx(iz+1-i) - 1 if(red(n).lt.syncmin) exit if(k.lt.200) k=k+1 candidate0(1,k)=n*df candidate0(2,k)=(jpeak(n)-1)*tstep candidate0(3,k)=red(n) enddo ncand=k ! Put nfqso at top of list, and save only the best of near-dupe freqs. do i=1,ncand if(abs(candidate0(1,i)-nfqso).lt.10.0) candidate0(1,i)=-candidate0(1,i) if(i.ge.2) then do j=1,i-1 fdiff=abs(candidate0(1,i))-abs(candidate0(1,j)) if(abs(fdiff).lt.4.0) then if(candidate0(3,i).ge.candidate0(3,j)) candidate0(3,j)=0. if(candidate0(3,i).lt.candidate0(3,j)) candidate0(3,i)=0. endif enddo ! write(*,3001) i,candidate0(1,i-1),candidate0(1,i),candidate0(3,i-1), & ! candidate0(3,i) !3001 format(i2,4f8.1) endif enddo fac=20.0/maxval(s) s=fac*s call indexx(candidate0(1,1:ncand),ncand,indx) do i=1,ncand j=indx(i) candidate(1,i)=abs(candidate0(1,j)) candidate(2,i)=candidate0(2,j) candidate(3,i)=candidate0(3,j) enddo return end subroutine sync8