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Modify jf49sim to use Watterson channel simulator.

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This commit is contained in:
Steven Franke 2020-04-26 14:17:39 -05:00
parent 2d2ac37539
commit 195e04902f
1 changed files with 31 additions and 79 deletions
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110
lib/jt49sim.f90
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@ -1,7 +1,8 @@
program jt49sim
! Generate simulated data for testing JT4 and JT9
! April 26, 2020: changed to Watterson channel simulator (K9AN)
!
use wavhdr
use packjt
use jt4
@ -13,21 +14,21 @@ program jt49sim
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 c0(NMAX) !Waveform multipled by fading realization
complex z
real*8 f0,dt,twopi,phi,dphi,baud,fsample,freq,dnsps
character message*22,fname*11,csubmode*2,arg*12
character msgsent*22
nargs=iargc()
if(nargs.ne. 7) then
print *, 'Usage: jt49sim "msg" nA-nE Nsigs fDop DT Nfiles SNR'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 4G 10 0.2 0.0 1 0'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 9A 1 0.0 0.0 1 -20'
if(nargs.ne. 8) then
print *, 'Usage: jt49sim "msg" nA-nE Nsigs fDop delay DT Nfiles SNR'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 4G 10 0.2 1.0 0.0 1 0'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 9A 1 0.0 0.0 0.0 1 -20'
print *, 'Use msg=@nnnn to generate a tone at nnnn Hz:'
print *, 'Example: jt49sim "@1500" 9A 1 10.0 0.0 1 -20'
print *, 'Example: jt49sim "@1500" 9A 1 10.0 0.0 0.0 1 -20'
print *, 'If Nsigs > 100, generate one signal with f0=Nsigs'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 4F 1800 0.2 0.0 1 -20'
print *, 'Example: jt49sim "K1ABC W9XYZ EN37" 4F 1800 0.2 0.0 0.0 1 -20'
go to 999
endif
call getarg(1,message)
@ -42,18 +43,19 @@ program jt49sim
call getarg(4,arg)
read(arg,*) fspread
call getarg(5,arg)
read(arg,*) xdt
read(arg,*) delay
call getarg(6,arg)
read(arg,*) nfiles
read(arg,*) xdt
call getarg(7,arg)
read(arg,*) nfiles
call getarg(8,arg)
read(arg,*) snrdb
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
h=default_header(12000,npts)
h=default_header(12000,NMAX)
dfsig=2000.0/nsigs !Freq spacing between sigs in file (Hz)
ichk=0
nsym=0
@ -69,9 +71,10 @@ program jt49sim
dnsps=6912.d0 !Samples per symbol
baud=12000.d0/dnsps !Keying rate = 1.736...
endif
NZ=nsym*dnsps
write(*,1000)
1000 format('File Sig Freq Mode S/N DT Dop Message'/60('-'))
1000 format('File Sig Freq Mode S/N DT fDop delay Message'/60('-'))
do ifile=1,nfiles !Loop over requested number of files
write(fname,1002) ifile !Output filename
@ -80,7 +83,7 @@ program jt49sim
xnoise=0.
cdat=0.
if(snrdb.lt.90) then
do i=1,npts
do i=1,NMAX
xnoise(i)=gran() !Generate gaussian noise
enddo
endif
@ -88,7 +91,7 @@ program jt49sim
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
if(nsigs.eq.1) f0=1500.0
if(nsigs.gt.100) f0=nsigs
xsnr=snrdb
if(snrdb.eq.0.0) xsnr=-20 - isig
@ -99,14 +102,14 @@ program jt49sim
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,a2,2x,f5.1,f6.2,f6.1,1x,a22)
write(*,1020) ifile,isig,f0,csubmode,xsnr,xdt,fspread,delay,message
1020 format(i4,i4,f10.3,2x,a2,2x,f5.1,f6.2,f6.1,1x,f6.1,2x,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()
do i=1,NMAX !Add this signal into cdat()
isym=i/dnsps + 1
if(isym.gt.nsym) exit
if(isym.ne.isym0) then
@ -124,73 +127,22 @@ program jt49sim
xphi=phi
z=cmplx(cos(xphi),sin(xphi))
k=k+1
if(k.ge.1) cdat(k)=cdat(k) + sig*z
if(k.ge.1) cdat(k)=cdat(k) + z
enddo
if(nsigs.gt.100) exit
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
c0=cdat
if(fspread.ne.0 .or. delay.ne.0) then !Apply specified Doppler spread
fs=12000.0
call watterson(c0,NMAX,NZ,fs,delay,fspread)
endif
dat=aimag(cdat) + xnoise !Add the generated noise
dat=sig*aimag(c0) + 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
if(snrdb.ge.90.0) iwave(1:NMAX)=nint(fac*dat(1:NMAX))
if(snrdb.lt.90.0) iwave(1:NMAX)=nint(rms*dat(1:NMAX))
write(10) h,iwave(1:NMAX) !Save the .wav file
close(10)
enddo