subroutine gen_ft8wave(itone,nsym,nsps,bt,fsample,f0,cwave,wave,icmplx,nwave) ! ! generate ft8 waveform using Gaussian-filtered frequency pulses. ! use timer_module, only: timer parameter(MAX_SECONDS=20,NTAB=65536) real wave(nwave) complex cwave(nwave),ctab(0:NTAB-1) real pulse(23040) real dphi(0:(nsym+2)*nsps-1) integer itone(nsym) data ibt0/0/ save pulse,twopi,dt,hmod,ibt0,ctab ibt=nint(10*bt) if(ibt0.ne.ibt) then twopi=8.0*atan(1.0) dt=1.0/fsample hmod=1.0 ! Compute the frequency-smoothing pulse do i=1,3*nsps tt=(i-1.5*nsps)/real(nsps) pulse(i)=gfsk_pulse(bt,tt) enddo ibt0=nint(10*bt) do i=0,NTAB-1 phi=i*twopi/NTAB ctab(i)=cmplx(cos(phi),sin(phi)) enddo endif ! Compute the smoothed frequency waveform. ! Length = (nsym+2)*nsps samples, first and last symbols extended dphi_peak=twopi*hmod/real(nsps) dphi=0.0 do j=1,nsym ib=(j-1)*nsps ie=ib+3*nsps-1 dphi(ib:ie) = dphi(ib:ie) + dphi_peak*pulse(1:3*nsps)*itone(j) enddo ! Add dummy symbols at beginning and end with tone values equal to 1st and last symbol, respectively dphi(0:2*nsps-1)=dphi(0:2*nsps-1)+dphi_peak*itone(1)*pulse(nsps+1:3*nsps) dphi(nsym*nsps:(nsym+2)*nsps-1)=dphi(nsym*nsps:(nsym+2)*nsps-1)+dphi_peak*itone(nsym)*pulse(1:2*nsps) ! Calculate and insert the audio waveform phi=0.0 dphi = dphi + twopi*f0*dt !Shift frequency up by f0 wave=0. if(icmplx .ne. 0) cwave=0. !Avoid writing to memory we may not have access to call timer('gen_loop',0) k=0 do j=nsps,nsps+nwave-1 !Don't include dummy symbols k=k+1 if(icmplx.eq.0) then wave(k)=sin(phi) else i=phi*float(NTAB)/twopi cwave(k)=ctab(i) endif phi=mod(phi+dphi(j),twopi) enddo call timer('gen_loop',1) ! Apply envelope shaping to the first and last symbols nramp=nint(nsps/8.0) if(icmplx.eq.0) then wave(1:nramp)=wave(1:nramp) * & (1.0-cos(twopi*(/(i,i=0,nramp-1)/)/(2.0*nramp)))/2.0 k1=nsym*nsps-nramp+1 wave(k1:k1+nramp-1)=wave(k1:k1+nramp-1) * & (1.0+cos(twopi*(/(i,i=0,nramp-1)/)/(2.0*nramp)))/2.0 else cwave(1:nramp)=cwave(1:nramp) * & (1.0-cos(twopi*(/(i,i=0,nramp-1)/)/(2.0*nramp)))/2.0 k1=nsym*nsps-nramp+1 cwave(k1:k1+nramp-1)=cwave(k1:k1+nramp-1) * & (1.0+cos(twopi*(/(i,i=0,nramp-1)/)/(2.0*nramp)))/2.0 endif return end subroutine gen_ft8wave