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https://github.com/saitohirga/WSJT-X.git
synced 2025-02-03 09:44:24 -05:00
102 lines
2.9 KiB
Fortran
102 lines
2.9 KiB
Fortran
program echosim
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! Generate simulated echo-mode files -- self-echo or "measure"
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use wavhdr
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parameter (NWAVE=27648,NMAX=32768,NZ=36000)
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type(hdr) h !Header for .wav file
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character arg*12,fname*17
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complex c0(0:NMAX-1)
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complex c(0:NMAX-1)
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! complex cwave(0:NWAVE-1)
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real*8 f0,dt,twopi,phi,dphi
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real wave(NZ)
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integer*2 iwave(NZ) !Generated full-length waveform
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equivalence (nDop0,iwave(1))
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equivalence (nDopAudio0,iwave(3))
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equivalence (nfrit0,iwave(5))
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equivalence (f10,iwave(7))
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equivalence (fspread0,iwave(9))
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! Get command-line argument(s)
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nargs=iargc()
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if(nargs.ne.6) then
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print*,'Usage: echosim f0 fdop fspread delay nfiles snr'
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print*,'Examples: echosim 1500 0.0 4.0 5.0 10 -22'
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go to 999
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endif
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call getarg(1,arg)
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read(arg,*) f0 !Tone frequency
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call getarg(2,arg)
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read(arg,*) fdop !Doppler shift (Hz)
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call getarg(3,arg)
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read(arg,*) fspread !Watterson frequency spread (Hz)
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call getarg(4,arg)
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read(arg,*) delay !Watterson delay (ms)
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call getarg(5,arg)
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read(arg,*) nfiles !Number of files
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call getarg(6,arg)
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read(arg,*) snrdb !SNR_2500
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twopi=8.d0*atan(1.d0)
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fs=12000.0 !Sample rate (Hz)
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dt=1.d0/fs !Sample interval (s)
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bandwidth_ratio=2500.0/(fs/2.0)
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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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dphi=twopi*(f0+fdop)*dt
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do ifile=1,nfiles
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phi=0.d0
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do i=0,NWAVE-1
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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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c0(i)=cmplx(cos(xphi),sin(xphi))
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enddo
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c0(NWAVE:)=0.
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if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c0,NMAX,NWAVE,fs,delay,fspread)
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c=sig*c0
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wave(1:NWAVE)=imag(c(1:NWAVE))
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peak=maxval(abs(wave))
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if(snrdb.lt.90) then
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do i=1,NWAVE !Add gaussian noise at specified SNR
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xnoise=gran()
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wave(i)=wave(i) + xnoise
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enddo
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do i=NWAVE+1,NZ
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xnoise=gran()
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wave(i)=xnoise
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enddo
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endif
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gain=100.0
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if(snrdb.lt.90.0) then
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wave=gain*wave
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else
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datpk=maxval(abs(wave))
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fac=32766.9/datpk
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wave=fac*wave
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endif
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if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
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iwave=nint(wave)
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nDop0=nint(fdop)
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nDopAudio0=0
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nfrit0=0
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f10=f0 + fdop
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fspread0=fspread
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h=default_header(12000,NMAX)
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write(fname,1102) 3*ifile
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1102 format('000000_',i6.6,'.wav')
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open(10,file=fname,status='unknown',access='stream')
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write(10) h,iwave !Save to *.wav file
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close(10)
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write(*,1110) ifile,xdt,f0,snrdb,fname
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1110 format(i4,f7.2,f8.2,f7.1,2x,a17)
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enddo
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999 end program echosim
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