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71 lines
1.3 KiB
Fortran
71 lines
1.3 KiB
Fortran
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subroutine genjtms3a(chansym,nsym,iwave,nwave)
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integer*1 chansym(nsym)
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integer*2 iwave(30*48000)
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real x(0:6191),x2(0:6191)
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complex c(0:3096),c2(0:6191) !Could be 0:3096 ???
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equivalence (x,c),(x2,c2)
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do j=1,nsym !Define the baseband signal
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i0=24*(j-1) !24 samples per symbol
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x(i0:i0+23)=2*chansym(j)-1
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enddo
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nfft=24*nsym
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fac=1.0/nfft
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x(0:nfft-1)=fac*x(0:nfft-1)
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call four2a(x,nfft,1,-1,0) !Forward r2c FFT
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! Apply lowpass filter
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fc=1200.0
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bw=200.0
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df=48000.0/nfft
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nh=nfft/2
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c2=0.
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ib=2000.0/df
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do i=0,ib
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f=i*df
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g=1.0
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if(f.gt.fc) then
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xx=(f-fc)/bw
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g=exp(-xx*xx)
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endif
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c2(i)=g*c(i)
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enddo
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call four2a(c2,nfft,1,1,-1) !Inverse c2r FFT
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nf0=nint(1500.0/df)
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f0=nf0*df
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twopi=8.0*atan(1.0)
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dphi=twopi*f0/48000.0
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phi=0.
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peak=0.
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sq=0.
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do i=0,nfft-1
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phi=phi+dphi
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if(phi.gt.twopi) phi=phi-twopi
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y=cos(phi)
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x2(i)=y*x2(i)
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sq=sq + x2(i)**2
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if(abs(x2(i)).gt.peak) peak=abs(x2(i))
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enddo
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rms=sqrt(sq/nfft)
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! print*,rms,peak,peak/rms
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fac=32767.0/peak
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do i=0,nfft-1
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iwave(i+1)=fac*x2(i)
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enddo
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nwave=30*48000
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nrpt=nwave/nfft
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do n=2,nrpt
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ib=n*nfft
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ia=ib-nfft+1
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iwave(ia:ib)=iwave(1:nfft)
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enddo
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return
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end subroutine genjtms3a
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