2017-06-15 08:09:53 -04:00
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subroutine sync8(iwave,xdt,f1,s)
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include 'ft8_params.f90'
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parameter (IZ=10,JZ=20)
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complex cx(0:NH1)
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real s(NH1,NHSYM)
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real savg(NH1)
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real x(NFFT1)
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real sync2d(-IZ:IZ,-JZ:JZ)
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integer*2 iwave(NMAX)
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integer icos7(0:6)
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data icos7/2,5,6,0,4,1,3/ !Costas 7x7 tone pattern
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equivalence (x,cx)
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! Compute symbol spectra at half-symbol steps.
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savg=0.
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istep=NSPS/2
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tstep=istep/12000.0
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df=12000.0/NFFT1
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fac=1.0/300.0
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do j=1,NHSYM
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ia=(j-1)*istep + 1
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ib=ia+NSPS-1
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x(1:NSPS)=fac*iwave(ia:ib)
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x(NSPS+1:)=0.
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call four2a(x,NFFT1,1,-1,0) !r2c FFT
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do i=1,NH1
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s(i,j)=real(cx(i))**2 + aimag(cx(i))**2
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enddo
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savg=savg + s(1:NH1,j)
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enddo
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ia=nint(30.0/df)
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ib=nint(3000.0/df)
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savg=savg/NHSYM
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pmax=0.
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i0=0
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do i=ia,ib
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p=sum(savg(i-8:i+8))/17.0
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if(p.gt.pmax) then
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pmax=p
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i0=i-7
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endif
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enddo
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tmax=0.
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ipk=0
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jpk=0
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2017-06-15 10:58:59 -04:00
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j0=1
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2017-06-15 08:09:53 -04:00
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do i=-IZ,IZ
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do j=-JZ,JZ
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t=0.
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do n=0,6
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k=j0+j+2*n
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if(k.ge.1) t=t + s(i0+i+2*icos7(n),k)
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t=t + s(i0+i+2*icos7(n),k+72)
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if(k+144.le.NHSYM) t=t + s(i0+i+2*icos7(n),k+144)
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enddo
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sync2d(i,j)=t
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if(t.gt.tmax) then
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tmax=t
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jpk=j
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ipk=i
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endif
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enddo
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enddo
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f0=i0*df
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f1=(i0+ipk)*df
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xdt=jpk*tstep
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return
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end subroutine sync8
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