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94 lines
2.6 KiB
Fortran
94 lines
2.6 KiB
Fortran
subroutine gen_fst4wave(itone,nsym,nsps,nwave,fsample,hmod,f0, &
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icmplx,cwave,wave)
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use prog_args
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parameter(NTAB=65536)
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real wave(nwave)
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complex cwave(nwave),ctab(0:NTAB-1)
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character(len=1) :: cvalue
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real, allocatable, save :: pulse(:)
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real, allocatable :: dphi(:)
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integer hmod
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integer itone(nsym)
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logical first, lshape
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data first/.true./
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data nsps0/-99/
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data lshape/.true./
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save first,twopi,dt,tsym,nsps0,ctab,lshape
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if(first) then
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twopi=8.0*atan(1.0)
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do i=0,NTAB-1
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phi=i*twopi/NTAB
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ctab(i)=cmplx(cos(phi),sin(phi))
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enddo
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call get_environment_variable("FST4_NOSHAPING",cvalue,nlen)
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if(nlen.eq.1 .and. cvalue.eq."1") lshape=.false.
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endif
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if(first.or.nsps.ne.nsps0) then
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if(allocated(pulse)) deallocate(pulse)
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allocate(pulse(1:3*nsps))
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dt=1.0/fsample
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tsym=nsps/fsample
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! Compute the smoothed frequency-deviation 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(2.0,tt)
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enddo
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first=.false.
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nsps0=nsps
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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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allocate( dphi(0:(nsym+2)*nsps-1) )
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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*(f0-1.5*hmod/tsym)*dt !Shift frequency up by f0
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if(icmplx.eq.0) wave=0.
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if(icmplx.eq.1) cwave=0.
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k=0
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do j=nsps,(nsym+1)*nsps-1
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k=k+1
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i=phi*float(NTAB)/twopi
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i=iand(i,NTAB-1)
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if(icmplx.eq.0) then
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wave(k)=aimag(ctab(i))
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else
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cwave(k)=ctab(i)
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endif
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phi=phi+dphi(j)
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if(phi.gt.twopi) phi=phi-twopi
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enddo
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! Compute the ramp-up and ramp-down symbols
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if(icmplx.eq.0) then
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if(lshape) then
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wave(1:nsps/4)=wave(1:nsps/4) * &
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(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
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k1=(nsym-1)*nsps+3*nsps/4+1
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wave(k1:k1+nsps/4)=wave(k1:k1+nsps/4) * &
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(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
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endif
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else
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if(lshape) then
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cwave(1:nsps/4)=cwave(1:nsps/4) * &
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(1.0-cos(twopi*(/(i,i=0,nsps/4-1)/)/real(nsps/2)))/2.0
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k1=(nsym-1)*nsps+3*nsps/4+1
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cwave(k1:k1+nsps/4)=cwave(k1:k1+nsps/4) * &
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(1.0+cos(twopi*(/(i,i=0,nsps/4)/)/real(nsps/2)))/2.0
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endif
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endif
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return
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end subroutine gen_fst4wave
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