WSJT-X/lib/jt65sim.f90
Joe Taylor 56e3638bc5 Increase the JT65 range of acceptable DT: now -2 to +5 s. Note that
displayed DT values appear to be to low by 0.2 s -- they range from
-2.2 s to +4.8 s, according to files generated by jt65sim.


git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6179 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2015-11-25 16:40:22 +00:00

196 lines
6.8 KiB
Fortran

program jt65sim
! Generate simulated JT65 data for testing WSJT-X
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(126) !Channel symbols (values 0-65)
integer dgen(12) !Twelve 6-bit data symbols
integer sent(63) !RS(63,12) codeword
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,sps
character msg*22,arg*8,fname*11,csubmode*1
integer nprc(126) !Sync pattern
data nprc/1,0,0,1,1,0,0,0,1,1,1,1,1,1,0,1,0,1,0,0, &
0,1,0,1,1,0,0,1,0,0,0,1,1,1,0,0,1,1,1,1, &
0,1,1,0,1,1,1,1,0,0,0,1,1,0,1,0,1,0,1,1, &
0,0,1,1,0,1,0,1,0,1,0,0,1,0,0,0,0,0,0,1, &
1,0,0,0,0,0,0,0,1,1,0,1,0,0,1,0,1,1,0,1, &
0,1,0,1,0,0,1,1,0,0,1,0,0,1,0,0,0,0,1,1, &
1,1,1,1,1,1/
nargs=iargc()
if(nargs.ne.6) then
print*,'Usage: jt65sim mode nsigs fspread SNR DT nfiles'
print*,'Example: jt65sim A 10 0.2 -24 0.0 1'
print*,'Enter SNR = 0 to generate a range of SNRs.'
go to 999
endif
csubmode='A'
call getarg(1,csubmode)
mode65=1
if(csubmode.eq.'B') mode65=2
if(csubmode.eq.'C') mode65=4
call getarg(2,arg)
read(arg,*) nsigs !Number of signals in each file
call getarg(3,arg)
read(arg,*) fspread !Doppler spread (Hz)
call getarg(4,arg)
read(arg,*) snrdb !S/N in dB (2500 hz reference BW)
call getarg(5,arg)
read(arg,*) xdt !Generated DT
call getarg(6,arg)
read(arg,*) nfiles !Number of files
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
baud=11025.d0/4096.d0 !Keying rate
sps=12000.d0/baud !Samples per symbol, at fsample=12000 Hz
nsym=126 !Number of channel symbols
h=default_header(12000,npts)
dfsig=2000.0/nsigs !Freq spacing between sigs in file (Hz)
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)
nsnr=nint(snrdb)
if(snrdb.eq.0.0) nsnr=-19 - isig
if(csubmode.eq.'B' .and. snrdb.eq.0.0) nsnr=-21 - isig
if(csubmode.eq.'C' .and. snrdb.eq.0.0) nsnr=-21 - isig
write(msg,1010) nsnr
1010 format('K1ABC W9XYZ ',i3.2)
call packmsg(msg,dgen,itype) !Pack message into 12 six-bit bytes
call rs_encode(dgen,sent) !Encode using RS(63,12)
call interleave63(sent,1) !Interleave channel symbols
call graycode65(sent,63,1) !Apply Gray code
k=0
do j=1,nsym !Insert sync and data into itone()
if(nprc(j).eq.0) then
k=k+1
itone(j)=sent(k)+2
else
itone(j)=0
endif
enddo
bandwidth_ratio=2500.0/6000.0
sig=sqrt(2*bandwidth_ratio)*10.0**(0.05*nsnr)
if(nsnr.gt.90.0) sig=1.0
write(*,1020) ifile,isig,f0,csubmode,nsnr,sig,msg
1020 format(i4,i4,f10.3,1x,a1,i5,f8.4,2x,a22)
phi=0.d0
dphi=0.d0
k=12000 + xdt*12000 !Start audio at t = xdt + 1.0 s
isym0=-99
do i=1,npts !Add this signal into cdat()
isym=nint(i/sps)+1
if(isym.gt.nsym) exit
if(isym.ne.isym0) then
freq=f0 + itone(isym)*baud*mode65
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.
do i=1,NH
f=i*df
x=-f/fspread
z=0.
a=0.
if(x.lt.50.0) then
a=sqrt(exp(-x*x))
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 jt65sim