mirror of https://github.com/saitohirga/WSJT-X.git
67 lines
1.8 KiB
Fortran
67 lines
1.8 KiB
Fortran
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subroutine ft2_iwave(msg37,f0,snrdb,iwave)
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! Generate waveform for experimental "FT2" mode
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use packjt77
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include 'ft2_params.f90' !Set various constants
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parameter (NWAVE=NN*NSPS)
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character msg37*37,msgsent37*37
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real wave(NMAX)
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integer itone(NN)
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integer*2 iwave(NMAX) !Generated full-length waveform
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twopi=8.0*atan(1.0)
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fs=12000.0 !Sample rate (Hz)
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dt=1.0/fs !Sample interval (s)
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hmod=0.8 !Modulation index (MSK=0.5, FSK=1.0)
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tt=NSPS*dt !Duration of symbols (s)
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baud=1.0/tt !Keying rate (baud)
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bw=1.5*baud !Occupied bandwidth (Hz)
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txt=NZ*dt !Transmission length (s)
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bandwidth_ratio=2500.0/(fs/2.0)
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sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*snrdb)
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if(snrdb.gt.90.0) sig=1.0
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txt=NN*NSPS/12000.0
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! Source-encode, then get itone():
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itype=1
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call genft2(msg37,0,msgsent37,itone,itype)
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k=0
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phi=0.0
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do j=1,NN !Generate real waveform
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dphi=twopi*(f0*dt+(hmod/2.0)*(2*itone(j)-1)/real(NSPS))
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do i=1,NSPS
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k=k+1
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wave(k)=sig*sin(phi)
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phi=mod(phi+dphi,twopi)
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enddo
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enddo
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kz=k
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peak=maxval(abs(wave(1:kz)))
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! nslots=1
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! if(width.gt.0.0) call filt8(f0,nslots,width,wave)
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if(snrdb.lt.90) then
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do i=1,NMAX !Add gaussian noise at specified SNR
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xnoise=gran()
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wave(i)=wave(i) + xnoise
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enddo
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endif
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gain=1.0
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if(snrdb.lt.90.0) then
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wave=gain*wave
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else
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datpk=maxval(abs(wave))
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fac=32767.0/datpk
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wave=fac*wave
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endif
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if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
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iwave(1:kz)=nint(wave(1:kz))
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return
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end subroutine ft2_iwave
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