45 lines
1.2 KiB
Fortran
45 lines
1.2 KiB
Fortran
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subroutine genbpsk(id,f00,ndiff,nref,c)
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parameter (ND=121) !Data symbols: LDPC (120,60), r=1/2
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parameter (NN=ND) !Total symbols (121)
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parameter (NSPS=28800) !Samples per symbol at 12000 sps
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parameter (NZ=NSPS*NN) !Samples in waveform (3456000)
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complex c(0:NZ-1) !Complex waveform
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real*8 twopi,dt,fs,baud,f0,dphi,phi
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integer id(NN) !Encoded NRZ data (values +/-1)
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integer ie(NN) !Differentially encoded data
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f0=f00
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twopi=8.d0*atan(1.d0)
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fs=12000.d0
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dt=1.0/fs
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baud=1.d0/(NSPS*dt)
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if(ndiff.ne.0) then
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ie(1)=1 !First bit is always 1
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do i=2,NN !Differentially encode
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ie(i)=id(i)*ie(i-1)
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enddo
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endif
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! Generate the BPSK waveform
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phi=0.d0
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k=-1
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do j=1,NN
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dphi=twopi*f0*dt
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x=id(j)
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if(ndiff.ne.0) x=ie(j) !Differential
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if(nref.ne.0) x=1.0 !Generate reference carrier
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do i=1,NSPS
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k=k+1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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xphi=phi
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c(k)=x*cmplx(cos(xphi),sin(xphi))
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enddo
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enddo
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return
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end subroutine genbpsk
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