program ft4sim ! Generate simulated signals for experimental "FT4" mode use wavhdr use packjt77 include 'ft4_params.f90' !Set various constants parameter (NWAVE=NN*NSPS) type(hdr) h !Header for .wav file character arg*12,fname*17 character msg37*37,msgsent37*37 character c77*77 complex c0(0:NMAX-1) complex c(0:NMAX-1) real wave(NMAX) real dphi(0:NMAX-1) real pulse(3*NSPS) integer itone(NN) integer*1 msgbits(77) integer*2 iwave(NMAX) !Generated full-length waveform integer icos4(4) data icos4/0,1,3,2/ ! Get command-line argument(s) nargs=iargc() if(nargs.ne.7) then print*,'Usage: ft4sim "message" f0 DT fdop del nfiles snr' print*,'Examples: ft4sim "CQ W9XYZ EN37" 1500 0.0 0.1 1.0 10 -15' print*,' ft4sim "K1ABC W9XYZ R 539 WI" 1500 0.0 0.1 1.0 10 -15' go to 999 endif call getarg(1,msg37) !Message to be transmitted call getarg(2,arg) read(arg,*) f0 !Frequency (only used for single-signal) call getarg(3,arg) read(arg,*) xdt !Time offset from nominal (s) call getarg(4,arg) read(arg,*) fspread !Watterson frequency spread (Hz) call getarg(5,arg) read(arg,*) delay !Watterson delay (ms) call getarg(6,arg) read(arg,*) nfiles !Number of files call getarg(7,arg) read(arg,*) snrdb !SNR_2500 nfiles=abs(nfiles) twopi=8.0*atan(1.0) fs=12000.0 !Sample rate (Hz) dt=1.0/fs !Sample interval (s) hmod=1.0 !Modulation index (0.5 is MSK, 1.0 is FSK) tt=NSPS*dt !Duration of symbols (s) baud=1.0/tt !Keying rate (baud) txt=NZ*dt !Transmission length (s) bandwidth_ratio=2500.0/(fs/2.0) sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*snrdb) if(snrdb.gt.90.0) sig=1.0 txt=NN*NSPS/12000.0 ! Source-encode, then get itone() i3=-1 n3=-1 call pack77(msg37,i3,n3,c77) read(c77,'(77i1)') msgbits call genft4(msg37,0,msgsent37,itone) write(*,*) write(*,'(a9,a37,3x,a7,i1,a1,i1)') 'Message: ',msgsent37,'i3.n3: ',i3,'.',n3 write(*,1000) f0,xdt,txt,snrdb 1000 format('f0:',f9.3,' DT:',f6.2,' TxT:',f6.1,' SNR:',f6.1) write(*,*) if(i3.eq.1) then write(*,*) ' mycall hiscall hisgrid' write(*,'(28i1,1x,i1,1x,28i1,1x,i1,1x,i1,1x,15i1,1x,3i1)') msgbits(1:77) else write(*,'(a14)') 'Message bits: ' write(*,'(77i1)') msgbits endif write(*,*) write(*,'(a17)') 'Channel symbols: ' write(*,'(76i1)') itone write(*,*) call sgran() ! The filtered frequency pulse do i=1,3*NSPS tt=(i-1.5*NSPS)/real(NSPS) pulse(i)=gfsk_pulse(1.0,tt) enddo ! Define the instantaneous frequency waveform dphi_peak=twopi*hmod/real(NSPS) dphi=0.0 do j=1,NN ib=(j-1)*NSPS ie=ib+3*NSPS-1 dphi(ib:ie)=dphi(ib:ie)+dphi_peak*pulse*itone(j) enddo phi=0.0 c0=0.0 dphi=dphi+twopi*f0*dt do j=0,NMAX-1 c0(j)=cmplx(cos(phi),sin(phi)) phi=mod(phi+dphi(j),twopi) enddo c0(0:NSPS-1)=c0(0:NSPS-1)*(1.0-cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS)) )/2.0 c0((NN+1)*NSPS:(NN+2)*NSPS-1)=c0((NN+1)*NSPS:(NN+2)*NSPS-1)*(1.0+cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS) ))/2.0 c0((NN+2)*NSPS:)=0. k=nint((xdt+0.14)/dt) c0=cshift(c0,-k) ia=k do ifile=1,nfiles c=c0 if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c,NMAX,NWAVE,fs,delay,fspread) c=sig*c ib=k wave=real(c) peak=maxval(abs(wave(ia:ib))) nslots=1 if(snrdb.lt.90) then do i=1,NMAX !Add gaussian noise at specified SNR xnoise=gran() wave(i)=wave(i) + xnoise enddo endif gain=100.0 if(snrdb.lt.90.0) then wave=gain*wave else datpk=maxval(abs(wave)) fac=32766.9/datpk wave=fac*wave endif if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped." iwave=nint(wave) h=default_header(12000,NMAX+2208) write(fname,1102) ifile 1102 format('000000_',i6.6,'.wav') open(10,file=fname,status='unknown',access='stream') write(10) h,iwave !Save to *.wav file iwave(1:2208)=0 write(10) iwave(1:2208) !Add 0.5 s of zeroes close(10) write(*,1110) ifile,xdt,f0,snrdb,fname 1110 format(i4,f7.2,f8.2,f7.1,2x,a17) enddo 999 end program ft4sim