WSJT-X/lib/ft4/ft4sim.f90

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4.6 KiB
Fortran
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program ft4sim
! Generate simulated signals for experimental "FT4" mode
use wavhdr
use packjt77
include 'ft4_params.f90' !Set various constants
parameter (NWAVE=NN*NSPS)
parameter (NZZ=18*3456) !62208
type(hdr) h !Header for .wav file
character arg*12,fname*17
character msg37*37,msgsent37*37
character c77*77
complex c0(0:NZZ-1)
complex c(0:NZZ-1)
real wave(NZZ)
real dphi(0:NZZ-1)
real pulse(3*NSPS)
integer itone(NN)
integer*1 msgbits(77)
integer*2 iwave(NZZ) !Generated full-length waveform
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integer icos4(4)
data icos4/0,1,3,2/
! Get command-line argument(s)
nargs=iargc()
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if(nargs.ne.7) then
print*,'Usage: ft4sim "message" f0 DT fdop del nfiles snr'
print*,'Examples: ft4sim "CQ W9XYZ EN37" 1500 0.0 0.1 1.0 10 -15'
print*,' ft4sim "K1ABC W9XYZ R 539 WI" 1500 0.0 0.1 1.0 10 -15'
go to 999
endif
call getarg(1,msg37) !Message to be transmitted
call getarg(2,arg)
read(arg,*) f0 !Frequency (only used for single-signal)
call getarg(3,arg)
read(arg,*) xdt !Time offset from nominal (s)
call getarg(4,arg)
read(arg,*) fspread !Watterson frequency spread (Hz)
call getarg(5,arg)
read(arg,*) delay !Watterson delay (ms)
call getarg(6,arg)
read(arg,*) nfiles !Number of files
call getarg(7,arg)
read(arg,*) snrdb !SNR_2500
nfiles=abs(nfiles)
twopi=8.0*atan(1.0)
fs=12000.0 !Sample rate (Hz)
dt=1.0/fs !Sample interval (s)
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hmod=1.0 !Modulation index (0.5 is MSK, 1.0 is FSK)
tt=NSPS*dt !Duration of symbols (s)
baud=1.0/tt !Keying rate (baud)
txt=NZ*dt !Transmission length (s)
bandwidth_ratio=2500.0/(fs/2.0)
sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*snrdb)
if(snrdb.gt.90.0) sig=1.0
txt=NN*NSPS/12000.0
! Source-encode, then get itone()
i3=-1
n3=-1
call pack77(msg37,i3,n3,c77)
read(c77,'(77i1)') msgbits
call genft4(msg37,0,msgsent37,itone)
write(*,*)
write(*,'(a9,a37,3x,a7,i1,a1,i1)') 'Message: ',msgsent37,'i3.n3: ',i3,'.',n3
write(*,1000) f0,xdt,txt,snrdb
1000 format('f0:',f9.3,' DT:',f6.2,' TxT:',f6.1,' SNR:',f6.1)
write(*,*)
if(i3.eq.1) then
write(*,*) ' mycall hiscall hisgrid'
write(*,'(28i1,1x,i1,1x,28i1,1x,i1,1x,i1,1x,15i1,1x,3i1)') msgbits(1:77)
else
write(*,'(a14)') 'Message bits: '
write(*,'(77i1)') msgbits
endif
write(*,*)
write(*,'(a17)') 'Channel symbols: '
write(*,'(76i1)') itone
write(*,*)
call sgran()
! The filtered frequency pulse
do i=1,3*NSPS
tt=(i-1.5*NSPS)/real(NSPS)
pulse(i)=gfsk_pulse(1.0,tt)
enddo
! Define the instantaneous frequency waveform
dphi_peak=twopi*hmod/real(NSPS)
dphi=0.0
do j=1,NN
ib=(j-1)*NSPS
ie=ib+3*NSPS-1
dphi(ib:ie)=dphi(ib:ie)+dphi_peak*pulse*itone(j)
enddo
phi=0.0
c0=0.0
dphi=dphi+twopi*f0*dt
! do j=0,NMAX-1 !### ??? ###
do j=0,(NN+2)*NSPS-1
c0(j)=cmplx(cos(phi),sin(phi))
phi=mod(phi+dphi(j),twopi)
enddo
c0(0:NSPS-1)=c0(0:NSPS-1)*(1.0-cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS)) )/2.0
c0((NN+1)*NSPS:(NN+2)*NSPS-1)=c0((NN+1)*NSPS:(NN+2)*NSPS-1)*(1.0+cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS) ))/2.0
c0((NN+2)*NSPS:)=0.
k=nint((xdt+0.35)/dt)
c0=cshift(c0,-k)
ia=k
do ifile=1,nfiles
c=c0
if(fspread.ne.0.0 .or. delay.ne.0.0) call watterson(c,NZZ,NWAVE,fs,delay,fspread)
c=sig*c
ib=k
wave=real(c)
peak=maxval(abs(wave(ia:ib)))
nslots=1
if(snrdb.lt.90) then
do i=1,NZZ !Add gaussian noise at specified SNR
xnoise=gran()
wave(i)=wave(i) + xnoise
enddo
endif
gain=100.0
if(snrdb.lt.90.0) then
wave=gain*wave
else
datpk=maxval(abs(wave))
fac=32766.9/datpk
wave=fac*wave
endif
if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
iwave=nint(wave)
h=default_header(12000,NZZ)
write(fname,1102) ifile
1102 format('000000_',i6.6,'.wav')
open(10,file=fname,status='unknown',access='stream')
write(10) h,iwave !Save to *.wav file
close(10)
write(*,1110) ifile,xdt,f0,snrdb,fname
1110 format(i4,f7.2,f8.2,f7.1,2x,a17)
enddo
999 end program ft4sim