Add ft4sim_mult, which is basically functional.

2026-07-30 05:54:22 -04:00 · 2019-01-30 15:33:47 -05:00
parent 3f7fb38e81
commit 189f538dc0
4 changed files with 296 additions and 1 deletions
@@ -0,0 +1,129 @@
+program ft4sim_mult
+
+! Generate simulated signals for experimental "FT4" mode 
+
+  use wavhdr
+  use packjt77
+  include 'ft4_params.f90'               !FT4 protocol constants
+  parameter (NWAVE=NN*NSPS)
+  parameter (NZZ=15*12000)               !Length of .wav file, 180,000 i*2 samples
+  type(hdr) h                            !Header for .wav file
+  character arg*12,fname*17,cjunk*4
+  character msg37*37,msgsent37*37,c77*77
+  real wave(NZZ)
+  real tmp(NZZ)
+  real dphi(0:NMAX-1)
+  real pulse(3*NSPS)               
+  integer itone(NN)
+  integer*2 iwave(NZZ)                  !Generated full-length waveform
+  integer icos4(4)
+  data icos4/0,1,3,2/
+  
+! Get command-line argument(s)
+  nargs=iargc()
+  if(nargs.ne.2) then
+     print*,'Usage:    ft4sim nsigs nfiles'
+     print*,'Example:  ft4sim  20     8 '
+     go to 999
+  endif
+  call getarg(1,arg)
+  read(arg,*) nsigs                      !Number of signals
+  call getarg(2,arg)
+  read(arg,*) nfiles                     !Number of files
+
+  twopi=8.0*atan(1.0)
+  fs=12000.0                             !Sample rate (Hz)
+  dt=1.0/fs                              !Sample interval (s)
+  hmod=1.0                               !Modulation index (0.5 is MSK, 1.0 is FSK)
+  tt=NSPS*dt                             !Duration of unsmoothed symbols (s)
+  baud=1.0/tt                            !Keying rate (baud)
+  txt=NZ*dt                              !Transmission length (s) without ramp up/down
+  bandwidth_ratio=2500.0/(fs/2.0)
+  txt=NN*NSPS/12000.0
+  xdtmax=10.0 - 0.086
+
+! Compute the filtered frequency pulse
+  do i=1,3*NSPS
+     tt=(i-1.5*NSPS)/real(NSPS)
+     pulse(i)=gfsk_pulse(1.0,tt)
+  enddo
+  open(10,file='messages.txt',status='old',err=998)
+
+  do ifile=1,nfiles
+1    read(10,1001,end=999) cjunk,n
+1001 format(a4,i2)
+     if(cjunk.ne.'File' .or. n.ne.ifile) go to 1
+     wave=0.
+     write(fname,1002) ifile
+1002 format('000000_',i6.6,'.wav')
+     
+     do isig=1,nsigs
+        read(10,1003,end=100) cjunk,isnr,xdt0,ifreq,msg37
+1003    format(a4,30x,i3,f5.1,i5,1x,a37)
+        if(cjunk.eq.'File') go to 100
+        if(isnr.lt.-16) isnr=-16
+        f0=ifreq*93.75/50.0
+        call random_number(r)
+        xdt=r*xdtmax
+! Source-encode, then get itone()
+        i3=-1
+        n3=-1
+        call pack77(msg37,i3,n3,c77)
+        call genft4(msg37,0,msgsent37,itone)
+
+! Compute the smoothed 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
+
+! Calculate and insert the audio waveform
+        phi=0.0
+        dphi=dphi+twopi*f0*dt
+        tmp=0.
+        k0=nint((xdt+0.043)/dt)
+        k=k0-1
+        do j=0,NMAX-1
+           k=k+1
+           tmp(k)=sin(phi)
+           phi=mod(phi+dphi(j),twopi)
+        enddo
+        k1=k
+
+! Compute the ramp-up and ramp-down symbols
+        tmp(k0-NSPS:k0-1)=tmp(k0-NSPS:k0-1) *                                        &
+             (1.0-cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS)))/2.0
+        tmp(k1+1:k1+NSPS)=tmp(k1+1:k1+NSPS) *                                        &
+             (1.0+cos(twopi*(/(i,i=0,NSPS-1)/)/(2.0*NSPS)))/2.0
+
+ ! Insert this signal into wave() array
+        sig=sqrt(2*bandwidth_ratio) * 10.0**(0.05*isnr)
+        wave=wave + sig*tmp
+        write(*,1100) fname,isig,isnr,nint(f0),msg37
+1100    format(a17,i4,i5,i6,2x,a37)
+     enddo   ! isig
+   
+100  backspace 10
+     do i=1,NMAX                   !Add gaussian noise at specified SNR
+        xnoise=gran()
+        wave(i)=wave(i) + xnoise
+     enddo
+
+     gain=30.0
+     wave=gain*wave
+     if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
+     iwave=nint(wave)
+     h=default_header(12000,NZZ)
+     open(12,file=fname,status='unknown',access='stream')
+     write(12) h,iwave                !Save to *.wav file
+     close(12)
+     print*,' '
+  enddo      ! ifile
+  go to 999
+
+998 print*,'Cannot open file "messages.txt"'
+
+999 end program ft4sim_mult