WSJT-X/lib/fsk4hf/wspr_fsk8_sim.f90

program wspr_fsk8_sim

! Generate simulated data for a 4-minute "WSPR-LF" mode using 8-FSK.
! Output is saved to a *.wav file.

  use wavhdr
  include 'wspr_fsk8_params.f90'         !Set various constants
  type(hdr) h                            !Header for .wav file
  character arg*12,fname*16
  character msg*22,msgsent*22
  complex c0(0:NZ-1)
  complex c(0:NZ-1)
  real*8 fMHz
  integer itone(NN)
  integer*2 iwave(NMAX)                  !Generated full-length waveform  

! Get command-line argument(s)
  nargs=iargc()
  if(nargs.ne.8) then
     print*,'Usage:   wspr5sim "message"       f0  DT fsp del  nwav nfiles snr'
     print*,'Example: wspr5sim "K1ABC FN42 30" 50 0.0 0.1 1.0  1      10   -33'
     go to 999
  endif
  call getarg(1,msg)                     !Message to be transmitted
  call getarg(2,arg)
  read(arg,*) f0                         !Freq relative to WSPR-band center (Hz)
  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,*) nwav                       !1 for *.wav file, 0 for *.c4 file
  call getarg(7,arg)
  read(arg,*) nfiles                     !Number of files
  call getarg(8,arg)
  read(arg,*) snrdb                      !SNR_2500

  twopi=8.0*atan(1.0)
  fs=12000.0/NDOWN                       !Sample rate after downsampling
  dt=1.0/fs                              !Sample interval (s)
  tt=NSPS*dt                             !Duration of symbols (s)
  baud=1.0/tt                            !Keying rate
  bw=8*baud
  txt=NZ*dt                              !Transmission length (s)
  bandwidth_ratio=2500.0/(fs/2.0)
  sig=sqrt(bandwidth_ratio) * 10.0**(0.05*snrdb)
  if(snrdb.gt.90.0) sig=1.0
  txt=NN*NSPS0/12000.0

  call genwspr_fsk8(msg,msgsent,itone)       !Encode the message, get itone
  write(*,1000) f0,xdt,txt,snrdb,bw,msgsent
1000 format('f0:',f9.3,'   DT:',f6.2,'   TxT:',f6.1,'   SNR:',f6.1,    &
          '  BW:',f4.1,2x,a22)


  phi=0.0
  c0=0.
  k=-1 + nint(xdt/dt)
  do j=1,NN                              !Generate OQPSK waveform from itone
     dphi=twopi*(f0+itone(j)*baud)*dt
     if(k.eq.0) phi=-dphi
     do i=1,NSPS
        k=k+1
        phi=phi+dphi
        if(phi.gt.twopi) phi=phi-twopi
        xphi=phi
        if(k.ge.0 .and. k.lt.NZ) c0(k)=cmplx(cos(xphi),sin(xphi))
     enddo
  enddo

  call sgran()
  do ifile=1,nfiles
    if(nwav.eq.0) then
      c=c0
      if( fspread .ne. 0.0 .or. delay .ne. 0.0 ) then
        call watterson(c,NZ,fs,delay,fspread)
      endif
      c=c*sig
      if( snrdb.lt.90) then
        do i=0,NZ-1
          xnoise=gran()
          ynoise=gran()
          c(i)=c(i)+cmplx(xnoise,ynoise)
        enddo
      endif
      write(fname,1100) ifile
1100  format('000000_',i4.4,'.c4')
      open(10,file=fname,status='unknown',access='stream')
      fMHz=1.866d0
      nmin=4
      write(10) fname,nmin,fMHz,c
    else
      call wspr_fsk8_wav(baud,xdt,f0,itone,snrdb,iwave)
      h=default_header(12000,NMAX)
      write(fname,1102) ifile
1102  format('000000_',i4.4,'.wav')
      open(10,file=fname,status='unknown',access='stream')
      write(10) h,iwave                !Save to *.wav file
      close(10)
    endif
    write(*,1110) ifile,xdt,f0,snrdb,fname
1110 format(i4,f7.2,f8.2,f7.1,2x,a16)
  enddo
       
999 end program wspr_fsk8_sim