WSJT-X/lib/qra/q65/q65sim.f90
2021-03-04 11:15:54 +00:00

210 lines
6.9 KiB
Fortran

program q65sim
! Generate simulated Q65 data for testing the decoder.
use wavhdr
use packjt
parameter (NMAX=300*12000) !Total samples in .wav file
type(hdr) h !Header for .wav file
integer*2 iwave(NMAX) !Generated waveform
integer itone(85) !Channel symbols (values 0-65)
integer y(63) !Codeword
integer istart !averaging compatible start seconds
integer imins !minutes for 15s period timestamp
integer isecs !seconds for 15s period timestamp
real*4 xnoise(NMAX) !Generated random noise
real*4 dat(NMAX) !Generated real data
complex cdat(NMAX) !Generated complex waveform
complex cspread(0:NMAX-1) !Complex amplitude for Rayleigh fading
complex z
real*8 f0,dt,twopi,phi,dphi,baud,fsample,freq
character msg*37,fname*17,csubmode*1,arg*12
character msgsent*37
nargs=iargc()
if(nargs.ne.10) then
print*,'Usage: q65sim "msg" A-E freq fDop DT f1 Stp TRp Nfile SNR'
print*,'Example: q65sim "K1ABC W9XYZ EN37" A 1500 0.0 0.0 0.0 1 60 1 -26'
print*,'Example: q65sim "ST" A 1500 0.0 0.0 0.0 1 60 1 -26'
print*,' fDop = Doppler spread'
print*,' f1 = Drift or Doppler rate (Hz/min)'
print*,' Stp = Step size (Hz)'
print*,' Stp = 0 implies no Doppler tracking'
print*,' Creates filenames which increment to permit averaging in first period'
print*,' If msg = ST program produces a single tone at freq'
go to 999
endif
call getarg(1,msg)
call getarg(2,csubmode)
mode65=2**(ichar(csubmode)-ichar('A'))
call getarg(3,arg)
read(arg,*) f0
call getarg(4,arg)
read(arg,*) fspread
call getarg(5,arg)
read(arg,*) xdt
call getarg(6,arg)
read(arg,*) f1
call getarg(7,arg)
read(arg,*) nstp
call getarg(8,arg)
read(arg,*) ntrperiod
call getarg(9,arg)
read(arg,*) nfiles
call getarg(10,arg)
read(arg,*) snrdb
if(ntrperiod.eq.15) then
nsps=1800
else if(ntrperiod.eq.30) then
nsps=3600
else if(ntrperiod.eq.60) then
nsps=7200
else if(ntrperiod.eq.120) then
nsps=16000
else if(ntrperiod.eq.300) then
nsps=41472
else
print*,'Invalid TR period'
go to 999
endif
rms=100.
fsample=12000.d0 !Sample rate (Hz)
npts=fsample*ntrperiod !Total samples in .wav file
nfft=npts
nh=nfft/2
dt=1.d0/fsample !Sample interval (s)
twopi=8.d0*atan(1.d0)
nsym=85 !Number of channel symbols
mode65=2**(ichar(csubmode) - ichar('A'))
ichk=0
call genq65(msg,ichk,msgsent,itone,i3,n3)
j=0
do i=1,85
if(itone(i).gt.0) then
j=j+1
y(j)=itone(i)-1
endif
enddo
write(*,1001) y(1:13),y(1:13)
1001 format('Generated message'/'6-bit: ',13i3/'binary: ',13b6.6)
write(*,1002) y
1002 format(/'Codeword:'/(20i3))
write(*,1003) itone
1003 format(/'Channel symbols:'/(20i3))
baud=12000.d0/nsps !Keying rate (6.67 baud fot 15-s sequences)
h=default_header(12000,npts)
write(*,1004)
1004 format('File TR Freq Mode S/N Dop DT f1 Stp Message'/70('-'))
do ifile=1,nfiles !Loop over requested number of files
istart = (ifile*ntrperiod*2) - (ntrperiod*2)
if(ntrperiod.lt.30) then !wdg was 60
imins=istart/60
isecs=istart-(60*imins)
write(fname,1005) imins,isecs !Construction of output filename for 15s periods with averaging
1005 format('000000_',i4.4, i2.2,'.wav')
else
write(fname,1106) istart/60 !Output filename to be compatible with averaging 30-300s periods
1106 format('000000_',i4.4,'.wav')
endif
open(10,file=trim(fname),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
bandwidth_ratio=2500.0/6000.0
sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*snrdb)
if(snrdb.gt.90.0) sig=1.0
write(*,1020) ifile,ntrperiod,f0,csubmode,snrdb,fspread,xdt,f1,nstp,trim(msgsent)
1020 format(i4,i6,f7.1,2x,a1,2x,f5.1,1x,f6.2,2f6.1,i4,2x,a)
phi=0.d0
dphi=0.d0
k=(xdt+0.5)*12000 !Start audio at t=xdt+0.5 s (TR=15 and 30 s)
if(ntrperiod.ge.60) k=(xdt+1.0)*12000 !TR 60+ 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_drift=f1*i*dt/60.0
if(nstp.ne.0) freq_drift=freq_drift - nstp*nint(freq_drift/nstp)
if (msg(1:2).eq.'ST') then
freq = f0 + freq_drift
else
freq = f0 + freq_drift + itone(isym)*baud*mode65
endif
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
phi1=twopi*rran() !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
phi2=twopi*rran()
z=a*cmplx(cos(phi2),sin(phi2))
endif
cspread(nfft-i)=z
enddo
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)
enddo
999 end program q65sim