96 lines
2.8 KiB
Fortran
96 lines
2.8 KiB
Fortran
subroutine syncjs8d(cd0,i0,ctwk,itwk,sync)
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! Compute sync power for a complex, downsampled JS8 signal.
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!include 'js8_params.f90'
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parameter(NP=NMAX/NDOWN,NSS=NSPS/NDOWN)
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complex cd0(0:NP-1)
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complex csynca(4*NSS),csyncb(4*NSS),csyncc(4*NSS)
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complex csync2(4*NSS)
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complex ctwk(4*NSS)
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complex z1,z2,z3
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logical first
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data first/.true./
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save first,twopi,csynca,csyncb,csyncc
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p(z1)=(real(z1)**2 + aimag(z1)**2) !Statement function for power
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integer icos7a(0:6), icos7b(0:6), icos7c(0:6)
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if(NCOSTAS.eq.1) then
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icos7a = (/4,2,5,6,1,3,0/) !Beginning Costas 7x7 tone pattern
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icos7b = (/4,2,5,6,1,3,0/) !Middle Costas 7x7 tone pattern
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icos7c = (/4,2,5,6,1,3,0/) !End Costas 7x7 tone pattern
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else
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icos7a = (/0,6,2,3,5,4,1/) !Beginning Costas 7x7 tone pattern
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icos7b = (/1,5,0,2,3,6,4/) !Middle Costas 7x7 tone pattern
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icos7c = (/2,5,0,6,4,1,3/) !End Costas 7x7 tone pattern
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endif
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if(NWRITELOG.eq.1) then
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write(*,*) '<DecodeDebug> syncjs8d costas', icos7a, icos7b, icos7c
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flush(6)
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endif
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! Set some constants and compute the csync array.
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if( first ) then
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twopi=8.0*atan(1.0)
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k=1
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phia=0.0
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phib=0.0
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phic=0.0
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!fs2=12000.0/NDOWN !Sample rate after downsampling
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!dt2=1/fs2 !Corresponding sample interval
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!taus=NDOWNSPS*dt2 !Symbol duration
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!baud=1.0/taus !Keying rate
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do i=0,6
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dphia=2*twopi*icos7a(i)/real(NSS)
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dphib=2*twopi*icos7b(i)/real(NSS)
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dphic=2*twopi*icos7c(i)/real(NSS)
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do j=1,NSS/2
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csynca(k)=cmplx(cos(phia),sin(phia)) !Waveform for Beginning 7x7 Costas array
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csyncb(k)=cmplx(cos(phib),sin(phib)) !Waveform for Middle 7x7 Costas array
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csyncc(k)=cmplx(cos(phic),sin(phic)) !Waveform for End 7x7 Costas array
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phia=mod(phia+dphia,twopi)
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phib=mod(phib+dphib,twopi)
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phic=mod(phia+dphic,twopi)
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k=k+1
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enddo
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enddo
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first=.false.
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endif
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i1=i0 !four Costas arrays
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i2=i0+36*NSS
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i3=i0+72*NSS
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z1=0.
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z2=0.
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z3=0.
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csync2=csynca
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if(itwk.eq.1) csync2=ctwk*csynca !Tweak the frequency
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if(i1.ge.0 .and. i1+8*NSS-1.le.NP-1) z1=sum(cd0(i1:i1+8*NSS-1:2)*conjg(csync2))
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csync2=csyncb
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if(itwk.eq.1) csync2=ctwk*csyncb !Tweak the frequency
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if(i2.ge.0 .and. i2+8*NSS-1.le.NP-1) z2=sum(cd0(i2:i2+8*NSS-1:2)*conjg(csync2))
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csync2=csyncc
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if(itwk.eq.1) csync2=ctwk*csyncc !Tweak the frequency
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if(i3.ge.0 .and. i3+8*NSS-1.le.NP-1) z3=sum(cd0(i3:i3+8*NSS-1:2)*conjg(csync2))
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sync = p(z1) + p(z2) + p(z3)
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return
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end subroutine syncjs8d
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