mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-08 18:16:02 -05:00
161 lines
5.2 KiB
Fortran
161 lines
5.2 KiB
Fortran
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program qra66sim
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! Generate simulated QRA66 data for testing the decoder.
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use wavhdr
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use packjt
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parameter (NMAX=15*12000) !180,000
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parameter (NFFT=NMAX,NH=NFFT/2)
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type(hdr) h !Header for .wav file
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integer*2 iwave(NMAX) !Generated waveform
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integer*4 itone(85) !Channel symbols (values 0-65)
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real*4 xnoise(NMAX) !Generated random noise
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real*4 dat(NMAX) !Generated real data
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complex cdat(NMAX) !Generated complex waveform
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complex cspread(0:NFFT-1) !Complex amplitude for Rayleigh fading
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complex z
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real*8 f0,dt,twopi,phi,dphi,baud,fsample,freq
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character msg*22,fname*13,csubmode*1,arg*12
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character msgsent*22
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nargs=iargc()
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if(nargs.ne.6) then
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print *, 'Usage: qra66sim "msg" A|B fDop DT Nfiles SNR'
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print *, 'Example qra66sim "K1ABC W9XYZ EN37" A 0.2 0.0 1 -10'
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go to 999
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endif
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call getarg(1,msg)
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call getarg(2,csubmode)
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mode66=2**(ichar(csubmode)-ichar('A'))
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call getarg(3,arg)
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read(arg,*) fspread
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call getarg(4,arg)
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read(arg,*) xdt
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call getarg(5,arg)
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read(arg,*) nfiles
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call getarg(6,arg)
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read(arg,*) snrdb
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rms=100.
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fsample=12000.d0 !Sample rate (Hz)
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dt=1.d0/fsample !Sample interval (s)
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twopi=8.d0*atan(1.d0)
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npts=NMAX !Total samples in .wav file
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nsps=1920
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baud=12000.d0/nsps !Keying rate = 6.25 baud
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nsym=85 !Number of channel symbols
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h=default_header(12000,npts)
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ichk=66 !Flag sent to genqra64
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write(*,1000)
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1000 format('File Freq A|B S/N DT Dop Message'/60('-'))
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do ifile=1,nfiles !Loop over requested number of files
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write(fname,1002) ifile !Output filename
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1002 format('000000_',i6.6)
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open(10,file=fname//'.wav',access='stream',status='unknown')
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xnoise=0.
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cdat=0.
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if(snrdb.lt.90) then
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do i=1,npts
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xnoise(i)=gran() !Generate gaussian noise
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enddo
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endif
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f0=1500.0
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bandwidth_ratio=2500.0/6000.0
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sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*snrdb)
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if(snrdb.gt.90.0) sig=1.0
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call genqra64(msg,ichk,msgsent,itone,itype)
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write(*,1020) ifile,f0,csubmode,xsnr,xdt,fspread,msgsent
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1020 format(i4,f10.3,2x,a1,2x,f5.1,f6.2,f6.1,1x,a22)
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phi=0.d0
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dphi=0.d0
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k=(xdt+0.5)*12000 !Start audio at t = xdt + 0.5 s
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isym0=-99
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do i=1,npts !Add this signal into cdat()
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isym=i/nsps + 1
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if(isym.gt.nsym) exit
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if(isym.ne.isym0) then
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freq=f0 + itone(isym)*baud*mode66
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dphi=twopi*freq*dt
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isym0=isym
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endif
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phi=phi + dphi
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if(phi.gt.twopi) phi=phi-twopi
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xphi=phi
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z=cmplx(cos(xphi),sin(xphi))
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k=k+1
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if(k.ge.1) cdat(k)=cdat(k) + sig*z
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enddo
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if(fspread.ne.0) then !Apply specified Doppler spread
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df=12000.0/nfft
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cspread(0)=1.0
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cspread(NH)=0.
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b=6.0 !Use truncated Lorenzian shape for fspread
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do i=1,NH
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f=i*df
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x=b*f/fspread
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z=0.
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a=0.
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if(x.lt.3.0) then !Cutoff beyond x=3
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a=sqrt(1.111/(1.0+x*x)-0.1) !Lorentzian amplitude
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call random_number(r1)
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phi1=twopi*r1 !Random phase
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z=a*cmplx(cos(phi1),sin(phi1))
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endif
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cspread(i)=z
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z=0.
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if(x.lt.3.0) then !Same thing for negative freqs
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call random_number(r2)
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phi2=twopi*r2
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z=a*cmplx(cos(phi2),sin(phi2))
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endif
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cspread(NFFT-i)=z
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enddo
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! do i=0,NFFT-1
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! f=i*df
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! if(i.gt.NH) f=(i-nfft)*df
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! s=real(cspread(i))**2 + aimag(cspread(i))**2
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! write(13,3000) i,f,s,cspread(i)
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!3000 format(i5,f10.3,3f12.6)
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! enddo
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! s=real(cspread(0))**2 + aimag(cspread(0))**2
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! write(13,3000) 1024,0.0,s,cspread(0)
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call four2a(cspread,NFFT,1,1,1) !Transform to time domain
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sum=0.
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do i=0,NFFT-1
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p=real(cspread(i))**2 + aimag(cspread(i))**2
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sum=sum+p
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enddo
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avep=sum/NFFT
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fac=sqrt(1.0/avep)
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cspread=fac*cspread !Normalize to constant avg power
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cdat=cspread*cdat !Apply Rayleigh fading
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! do i=0,NFFT-1
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! p=real(cspread(i))**2 + aimag(cspread(i))**2
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! write(14,3010) i,p,cspread(i)
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!3010 format(i8,3f12.6)
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! enddo
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endif
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dat=aimag(cdat) + xnoise !Add generated AWGN noise
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fac=32767.0
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if(snrdb.ge.90.0) iwave(1:npts)=nint(fac*dat(1:npts))
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if(snrdb.lt.90.0) iwave(1:npts)=nint(rms*dat(1:npts))
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write(10) h,iwave(1:npts) !Save the .wav file
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close(10)
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! do i=1,NMAX
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! write(15,3020) i/12000.0,iwave(i)
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!3020 format(f10.6,i8)
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! enddo
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enddo
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999 end program qra66sim
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