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53 lines
1.3 KiB
Fortran
53 lines
1.3 KiB
Fortran
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subroutine gen_ft4wave(itone,nsym,nsps,fsample,f0,wave,nwave)
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real wave(nwave)
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real pulse(6144) !512*4*3
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real dphi(0:240000-1)
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integer itone(nsym)
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logical first
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data first/.true./
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save pulse,first,twopi,dt,hmod
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if(first) then
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twopi=8.0*atan(1.0)
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dt=1.0/fsample
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hmod=1.0
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! Compute the frequency-smoothing pulse
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do i=1,3*nsps
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tt=(i-1.5*nsps)/real(nsps)
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pulse(i)=gfsk_pulse(1.0,tt)
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enddo
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first=.false.
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endif
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! Compute the smoothed frequency waveform.
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! Length = (nsym+2)*nsps samples, zero-padded
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dphi_peak=twopi*hmod/real(nsps)
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dphi=0.0
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do j=1,nsym
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ib=(j-1)*nsps
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ie=ib+3*nsps-1
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dphi(ib:ie) = dphi(ib:ie) + dphi_peak*pulse(1:3*nsps)*itone(j)
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enddo
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! Calculate and insert the audio waveform
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phi=0.0
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dphi = dphi + twopi*f0*dt !Shift frequency up by f0
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wave=0.
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k=0
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do j=0,nwave-1
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k=k+1
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wave(k)=sin(phi)
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phi=mod(phi+dphi(j),twopi)
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enddo
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! Compute the ramp-up and ramp-down symbols
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wave(1:nsps)=wave(1:nsps) * &
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(1.0-cos(twopi*(/(i,i=0,nsps-1)/)/(2.0*nsps)))/2.0
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k1=(nsym+1)*nsps+1
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wave(k1:k1+nsps-1)=wave(k1:k1+nsps-1) * &
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(1.0+cos(twopi*(/(i,i=0,nsps-1)/)/(2.0*nsps)))/2.0
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return
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end subroutine gen_ft4wave
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