Fix some indexing problems. Create subroutine ft2_gfsk_iwave.f90 for use with ft2.exe. Needs testing.

CMakeLists.txt

@@ -469,6 +469,7 @@ set (wsjt_FSRCS
   lib/geodist.f90
   lib/getlags.f90
   lib/getmet4.f90
+  lib/ft2/gfsk_pulse.f90
   lib/graycode.f90
   lib/graycode65.f90
   lib/grayline.f90

lib/fsk4hf/ft2sim.f90

@@ -1,10 +1,3 @@
-real function gfsk_pulse(b,t)
-pi=4.*atan(1.0)
-c=pi*sqrt(2.0/log(2.0))
-gfsk_pulse=0.5*(erf(c*b*(t+0.5))-erf(c*b*(t-0.5)))
-return
-end function gfsk_pulse
-
 program ft2sim
 
 ! Generate simulated signals for experimental "FT2" mode 
@@ -114,8 +107,8 @@ program ft2sim
   enddo 
  
   c0(0:159)=c0(0:159)*(1.0-cos(twopi*(/(i,i=0,159)/)/320.0) )/2.0
-  c0(144*160:144*160+159)=c0(144*160:144*160+159)*(1.0+cos(twopi*(/(i,i=0,159)/)/320.0 ))/2.0
-  c0(145*160:)=0.
+  c0(145*160:145*160+159)=c0(145*160:145*160+159)*(1.0+cos(twopi*(/(i,i=0,159)/)/320.0 ))/2.0
+  c0(146*160:)=0.
 
   k=nint((xdt+0.25)/dt)
   c0=cshift(c0,-k)

lib/ft2/ft2_gfsk_iwave.f90

@@ -0,0 +1,88 @@
+subroutine ft2_gfsk_iwave(msg37,f0,snrdb,iwave)
+
+! Generate waveform for experimental "FT2" mode 
+
+  use packjt77
+  include 'ft2_params.f90'               !Set various constants
+  parameter (NWAVE=(NN+2)*NSPS)
+  character msg37*37,msgsent37*37
+  real wave(NWAVE),xnoise(NWAVE)
+  real dphi(NWAVE)
+  real pulse(480)
+
+  integer itone(NN)
+  integer*2 iwave(NWAVE)                 !Generated full-length waveform
+  logical first
+  data first/.true./
+  save pulse
+ 
+  twopi=8.0*atan(1.0)
+  fs=12000.0                             !Sample rate (Hz)
+  dt=1.0/fs                              !Sample interval (s)
+  hmod=0.8                               !Modulation index (MSK=0.5, FSK=1.0)
+  tt=NSPS*dt                             !Duration of symbols (s)
+  baud=1.0/tt                            !Keying rate (baud)
+  bw=1.5*baud                            !Occupied bandwidth (Hz)
+  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
+
+  if(first) then
+! The filtered frequency pulse
+     do i=1,480
+        tt=(i-240.5)/160.0
+        pulse(i)=gfsk_pulse(1.0,tt)
+     enddo
+     dphi_peak=twopi*(hmod/2.0)/real(NSPS)
+     first=.false.
+  endif
+
+! Source-encode, then get itone():
+  itype=1
+  call genft2(msg37,0,msgsent37,itone,itype)
+
+! Create the instantaneous frequency waveform
+  dphi=0.0
+  do j=1,NN
+     ib=(j-1)*160+1
+     ie=ib+480-1
+     dphi(ib:ie)=dphi(ib:ie)+dphi_peak*pulse*(2*itone(j)-1)
+  enddo
+
+  phi=0.0
+  wave=0.0
+  sqrt2=sqrt(2.)
+  dphi=dphi+twopi*f0*dt
+  do j=1,NWAVE
+     wave(j)=sqrt2*sin(phi)
+     sqsig=sqsig + wave(j)**2
+     phi=mod(phi+dphi(j),twopi)
+  enddo
+  wave(1:160)=wave(1:160)*(1.0-cos(twopi*(/(i,i=0,159)/)/320.0) )/2.0
+  wave(145*160+1:146*160)=wave(145*160+1:146*160)*(1.0+cos(twopi*(/(i,i=0,159)/)/320.0 ))/2.0
+  wave(146*160+1:)=0.
+
+  if(snrdb.gt.90.0) then
+     iwave=nint((32767.0/sqrt(2.0))*wave)
+     return
+  endif
+  
+  sqnoise=1.e-30
+  if(snrdb.lt.90) then
+     do i=1,NWAVE                   !Add gaussian noise at specified SNR
+        xnoise(i)=gran()            !Noise has rms = 1.0
+     enddo
+  endif
+  xnoise=xnoise*sqrt(0.5*fs/2500.0)
+  fac=30.0
+  snr_amplitude=10.0**(0.05*snrdb)
+  wave=fac*(snr_amplitude*wave + xnoise)
+  datpk=maxval(abs(wave))
+  print*,'A',snr_amplitude,datpk
+
+  iwave=nint((30000.0/datpk)*wave)
+  
+  return
+end subroutine ft2_gfsk_iwave

lib/ft2/gfsk_pulse.f90

@@ -0,0 +1,6 @@
+real function gfsk_pulse(b,t)
+  pi=4.*atan(1.0)
+  c=pi*sqrt(2.0/log(2.0))
+  gfsk_pulse=0.5*(erf(c*b*(t+0.5))-erf(c*b*(t-0.5)))
+  return
+end function gfsk_pulse