program jt4sim
! Generate simulated jt4 data for testing the decoder using new fading models
! Based on qra64sim with appropriate changes for JT4
! Includes option to generate 1000Hz single tone with "ST" as the message
use wavhdr
use packjt
use jt4
parameter (NMAX=60*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(206) !Channel symbols (values 0-8)
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 message*22,fname*11,csubmode*1,arg*12
character msgsent*22
nargs=iargc()
if(nargs.ne. 7) then
print *, 'Usage: jt4sim "msg" A-E Nsigs fDop DT Nfiles SNR'
print *, 'Example jt4sim "K1ABC W9XYZ EN37" A 10 0.2 0.0 1 0'
print *, 'Example jt4sim "ST" A 10 0.2 0.0 1 0'
go to 999
endif
call getarg(1,message)
call fmtmsg(message, iz)
call getarg(2,csubmode)
mode4=ichar(csubmode) - ichar('A') + 1
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(mode4.ge.8) nsigs=1 ! temporary - will need sorting out
rms=100.
fsample=12000.d0 !Sample rate (Hz)
dt=1.d0/fsample !Sample interval (s)
twopi=8.d0*atan(1.d0)
npts=60*12000 !Total samples in .wav file
nsps=12000.d0/4.375d0
baud=12000.d0/nsps !Keying rate = 1.7361111111
nsym=206 !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 gen4(message,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,message
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
if(message(1:2).eq.'ST') then !Finds ST in message string for single tone
freq=1000 !1000Hz for single tone
else
freq=f0 + itone(isym)*baud*nch(mode4)
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
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 !Lorenzian 3/28 onward
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(1:NFFT)=cspread*cdat(1:NFFT) !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 jt4sim