83 lines
2.0 KiB
Fortran
83 lines
2.0 KiB
Fortran
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subroutine getfc2w(c,csync,npeaks,fs,fc1,fpks)
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include 'wsprlf_params.f90'
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complex c(0:NZ-1) !Complex waveform
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complex cs(0:NZ-1) !For computing spectrum
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complex csync(0:NZ-1) !Sync symbols only, from cbb
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real a(5)
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real freqs(413),sp2(413),fpks(npeaks)
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integer pkloc(1)
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df=fs/NZ
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baud=fs/NSPS
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a(1)=-fc1
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a(2:5)=0.
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call twkfreq1(c,NZ,fs,a,cs) !Mix down by fc1
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! Filter, square, then FFT to get refined carrier frequency fc2.
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call four2a(cs,NZ,1,-1,1) !To freq domain
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ia=nint(0.75*baud/df)
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cs(ia:NZ-1-ia)=0. !Save only freqs around fc1
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call four2a(cs,NZ,1,1,1) !Back to time domain
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cs=cs/NZ
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cs=cs*cs !Square the data
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call four2a(cs,NZ,1,-1,1) !Compute squared spectrum
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! Find two peaks separated by baud
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pmax=0.
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fc2=0.
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ja=nint(0.3*baud/df)
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k=1
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do j=-ja,ja
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f2=j*df
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ia=nint((f2-0.5*baud)/df)
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if(ia.lt.0) ia=ia+NZ
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ib=nint((f2+0.5*baud)/df)
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p=real(cs(ia))**2 + aimag(cs(ia))**2 + &
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real(cs(ib))**2 + aimag(cs(ib))**2
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if(p.gt.pmax) then
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pmax=p
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fc2=0.5*f2
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endif
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freqs(k)=0.5*f2
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sp2(k)=p
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k=k+1
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! write(52,1200) f2,p,db(p)
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!1200 format(f10.3,2f15.3)
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enddo
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do i=1,npeaks
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pkloc=maxloc(sp2)
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ipk=pkloc(1)
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fpks(i)=freqs(ipk)
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ipk0=max(1,ipk-1)
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ipk1=min(413,ipk+1)
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! ipk0=ipk
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! ipk1=ipk
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sp2(ipk0:ipk1)=0.0
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!write(*,*) i,fpks(i),fc2
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enddo
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a(1)=-fc1
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a(2:5)=0.
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call twkfreq1(c,NZ,fs,a,cs) !Mix down by fc1
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cs=cs*conjg(csync)
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call four2a(cs,NZ,1,-1,1) !To freq domain
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pmax=0.
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do i=0,NZ-1
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f=i*df
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if(i.gt.NZ/2) f=(i-NZ)*df
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p=real(cs(i))**2 + aimag(cs(i))**2
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! write(51,3001) f,p,db(p)
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!3001 format(f10.3,e12.3,f10.3)
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if(p.gt.pmax) then
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pmax=p
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fc3=f
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endif
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enddo
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return
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end subroutine getfc2w
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