program qra64sim ! Generate simulated QRA64 data for testing the decoder. use wavhdr use packjt parameter (NMAX=54*12000) ! = 648,000 parameter (NFFT=10*65536,NH=NFFT/2) type(hdr) h !Header for .wav file integer*2 iwave(NMAX) !Generated waveform integer*4 itone(84) !Channel symbols (values 0-63) 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*11,csubmode*1,arg*12 character msgsent*22 nargs=iargc() if(nargs.ne. 7) then print *, 'Usage: qra64sim "msg" A-E Nsigs fDop DT Nfiles SNR' print *, 'Example qra64sim "K1ABC W9XYZ EN37" A 10 0.2 0.0 1 0' go to 999 endif call getarg(1,msg) call getarg(2,csubmode) mode64=2**(ichar(csubmode)-ichar('A')) call getarg(3,arg) read(arg,*) nsigs call getarg(4,arg) read(arg,*) fspread call getarg(5,arg) read(arg,*) xdt call getarg(6,arg) read(arg,*) nfiles call getarg(7,arg) read(arg,*) snrdb if(mode64.ge.8) nsigs=1 rms=100. fsample=12000.d0 !Sample rate (Hz) dt=1.d0/fsample !Sample interval (s) twopi=8.d0*atan(1.d0) npts=54*12000 !Total samples in .wav file nsps=6912 baud=12000.d0/nsps !Keying rate = 1.7361111111 nsym=84 !Number of channel symbols h=default_header(12000,npts) dfsig=2000.0/nsigs !Freq spacing between sigs in file (Hz) ichk=0 write(*,1000) 1000 format('File Sig Freq A-E 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_',i4.4) 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 do isig=1,nsigs !Generate requested number of sigs if(mod(nsigs,2).eq.0) f0=1500.0 + dfsig*(isig-0.5-nsigs/2) if(mod(nsigs,2).eq.1) f0=1500.0 + dfsig*(isig-(nsigs+1)/2) if(nsigs.eq.1) f0=1000.0 xsnr=snrdb if(snrdb.eq.0.0) xsnr=-20 - isig call genqra64(msg,ichk,msgsent,itone,itype) bandwidth_ratio=2500.0/6000.0 sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*xsnr) if(xsnr.gt.90.0) sig=1.0 write(*,1020) ifile,isig,f0,csubmode,xsnr,xdt,fspread,msg 1020 format(i4,i4,f10.3,2x,a1,2x,f5.1,f6.2,f6.1,1x,a22) phi=0.d0 dphi=0.d0 k=(xdt+1.0)*12000 !Start audio at t = xdt + 1.0 s isym0=-99 do i=1,npts !Add this signal into cdat() isym=i/nsps + 1 if(isym.gt.nsym) exit if(isym.ne.isym0) then freq=f0 + itone(isym)*baud*mode64 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 enddo if(fspread.ne.0) then !Apply specified Doppler spread df=12000.0/nfft twopi=8*atan(1.0) 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 call random_number(r1) phi1=twopi*r1 z=a*cmplx(cos(phi1),sin(phi1)) endif cspread(i)=z z=0. if(x.lt.50.0) then 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(1:npts)*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 the generated noise fac=32767.0/nsigs 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) enddo 999 end program qra64sim