program qra66sim ! Generate simulated QRA66 data for testing the decoder. use wavhdr use packjt parameter (NMAX=15*12000) !180,000 parameter (NFFT=NMAX,NH=NFFT/2) type(hdr) h !Header for .wav file integer*2 iwave(NMAX) !Generated waveform integer*4 itone(85) !Channel symbols (values 0-65) real*4 xnoise(NMAX) !Generated random noise real*4 dat(NMAX) !Generated real data complex cdat(NMAX) !Generated complex waveform complex cspread(0:NFFT-1) !Complex amplitude for Rayleigh fading complex z real*8 f0,dt,twopi,phi,dphi,baud,fsample,freq character msg*22,fname*13,csubmode*1,arg*12 character msgsent*22 nargs=iargc() if(nargs.ne.6) then print *, 'Usage: qra66sim "msg" A|B fDop DT Nfiles SNR' print *, 'Example qra66sim "K1ABC W9XYZ EN37" A 0.2 0.0 1 -10' go to 999 endif call getarg(1,msg) call getarg(2,csubmode) mode66=2**(ichar(csubmode)-ichar('A')) call getarg(3,arg) read(arg,*) fspread call getarg(4,arg) read(arg,*) xdt call getarg(5,arg) read(arg,*) nfiles call getarg(6,arg) read(arg,*) snrdb rms=100. fsample=12000.d0 !Sample rate (Hz) dt=1.d0/fsample !Sample interval (s) twopi=8.d0*atan(1.d0) npts=NMAX !Total samples in .wav file nsps=1920 nsym=85 !Number of channel symbols if(csubmode.eq.'B') then nsps=960 nsym=169 endif baud=12000.d0/nsps !Keying rate = 6.25 baud h=default_header(12000,npts) ichk=66 !Flag sent to genqra64 write(*,1000) 1000 format('File Freq A|B S/N DT Dop Message'/60('-')) do ifile=1,nfiles !Loop over requested number of files write(fname,1002) ifile !Output filename 1002 format('000000_',i6.6) open(10,file=fname//'.wav',access='stream',status='unknown') xnoise=0. cdat=0. if(snrdb.lt.90) then do i=1,npts xnoise(i)=gran() !Generate gaussian noise enddo endif f0=1500.0 bandwidth_ratio=2500.0/6000.0 sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*snrdb) if(snrdb.gt.90.0) sig=1.0 call genqra64(msg,ichk,msgsent,itone,itype) write(*,1020) ifile,f0,csubmode,xsnr,xdt,fspread,msgsent 1020 format(i4,f10.3,2x,a1,2x,f5.1,f6.2,f6.1,1x,a22) phi=0.d0 dphi=0.d0 k=(xdt+0.5)*12000 !Start audio at t = xdt + 0.5 s isym0=-99 do i=1,npts !Add this signal into cdat() isym=i/nsps + 1 if(isym.gt.nsym) exit if(csubmode.eq.'B' .and. isym.gt.84) isym=isym-84 if(isym.ne.isym0) then freq=f0 + itone(isym)*baud dphi=twopi*freq*dt isym0=isym endif phi=phi + dphi if(phi.gt.twopi) phi=phi-twopi xphi=phi z=cmplx(cos(xphi),sin(xphi)) k=k+1 if(k.ge.1) cdat(k)=cdat(k) + sig*z enddo if(fspread.ne.0) then !Apply specified Doppler spread df=12000.0/nfft cspread(0)=1.0 cspread(NH)=0. b=6.0 !Use truncated Lorenzian shape for fspread do i=1,NH f=i*df x=b*f/fspread z=0. a=0. if(x.lt.3.0) then !Cutoff beyond x=3 a=sqrt(1.111/(1.0+x*x)-0.1) !Lorentzian amplitude call random_number(r1) phi1=twopi*r1 !Random phase z=a*cmplx(cos(phi1),sin(phi1)) endif cspread(i)=z z=0. if(x.lt.3.0) then !Same thing for negative freqs call random_number(r2) phi2=twopi*r2 z=a*cmplx(cos(phi2),sin(phi2)) endif cspread(NFFT-i)=z enddo ! do i=0,NFFT-1 ! f=i*df ! if(i.gt.NH) f=(i-nfft)*df ! s=real(cspread(i))**2 + aimag(cspread(i))**2 ! write(13,3000) i,f,s,cspread(i) !3000 format(i5,f10.3,3f12.6) ! enddo ! s=real(cspread(0))**2 + aimag(cspread(0))**2 ! write(13,3000) 1024,0.0,s,cspread(0) call four2a(cspread,NFFT,1,1,1) !Transform to time domain sum=0. do i=0,NFFT-1 p=real(cspread(i))**2 + aimag(cspread(i))**2 sum=sum+p enddo avep=sum/NFFT fac=sqrt(1.0/avep) cspread=fac*cspread !Normalize to constant avg power cdat=cspread*cdat !Apply Rayleigh fading ! do i=0,NFFT-1 ! p=real(cspread(i))**2 + aimag(cspread(i))**2 ! write(14,3010) i,p,cspread(i) !3010 format(i8,3f12.6) ! enddo endif dat=aimag(cdat) + xnoise !Add generated AWGN noise fac=32767.0 if(snrdb.ge.90.0) iwave(1:npts)=nint(fac*dat(1:npts)) if(snrdb.lt.90.0) iwave(1:npts)=nint(rms*dat(1:npts)) write(10) h,iwave(1:npts) !Save the .wav file close(10) ! do i=1,NMAX ! write(15,3020) i/12000.0,iwave(i) !3020 format(f10.6,i8) ! enddo enddo 999 end program qra66sim