WSJT-X/libm65/genjt8.f90
Joe Taylor 000502af77 Morphing toward a usable WSJT-X with JT8 modes.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@2594 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2012-09-24 19:11:31 +00:00

97 lines
2.3 KiB
Fortran

subroutine genjt8(message,iwave,nwave,nbit,msgsent)
! Generate a JT8 wavefile.
parameter (NMAX=60*12000) !Max length of wave file
character*24 message !Message to be generated
character*24 msgsent !Message as it will be received
character cmode*5
real*8 t,dt,phi,f,f0,dfgen,dphi,twopi,tsymbol
integer*2 iwave(NMAX) !Generated wave file
integer iu(3)
integer gsym(372) !372 is needed for JT8 mode
integer sent(144)
integer ic8(8)
data ic8/3,6,2,4,5,0,7,1/
data nsps/4096/
data twopi/6.283185307d0/
save
cmode='JT8' !### temp ? ###
call srcenc(cmode,message,nbit,iu)
! In JT8 mode, message length is always nbit=78
if(nbit.ne.78) then
print*,'genjt8, nbit=',nbit
stop
endif
! Apply FEC and do the channel encoding
call chenc(cmode,nbit,iu,gsym)
! Remove source encoding, recover the human-readable message.
call srcdec(cmode,nbit,iu,msgsent)
! Insert 8x8 Costas array at beginning and end of array sent().
sent(1:8)=ic8
sent(135:142)=ic8
! Insert two symbols after each Costas array to specify message length.
if(nbit.eq.30) then
sent(9)=2
sent(10)=2
sent(143)=2
sent(144)=2
else if(nbit.eq.48) then
sent(9)=3
sent(10)=3
sent(143)=3
sent(144)=3
else
sent(9)=6
sent(10)=6
sent(143)=6
sent(144)=6
endif
! Insert the 3-bit data symbols
sent(11:134)=gsym(1:124)
! Use the four free symbols in 30-bit mode
if(nbit.eq.30) then
sent(121)=sent(20)
sent(122)=sent(45)
sent(123)=sent(70)
sent(124)=sent(95)
endif
! Set up necessary constants
nsym=144
tsymbol=nsps/12000.d0
dt=1.d0/12000.d0
f0=1270.46d0
dfgen=12000.d0/nsps
t=0.d0
phi=0.d0
k=0
j0=0
ndata=(nsym*12000.d0*tsymbol)/2
ndata=2*ndata
do i=1,ndata
t=t+dt
j=int(t/tsymbol) + 1 !Symbol number, 1-nsym
if(j.ne.j0) then
f=f0
k=k+1
if(k.le.144) f=f0+(sent(k))*dfgen !### Fix need for this ###
dphi=twopi*dt*f
j0=j
endif
phi=phi+dphi
iwave(i)=32767.0*sin(phi)
enddo
iwave(ndata+1:)=0
nwave=ndata+6000 !0.5 s buffer before CW ID
return
end subroutine genjt8