WSJT-X/libm65/genmsk.f90
Joe Taylor bcb97a148a Change from even to odd parity. Code for <space> is now 1011000.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/jtms3@2525 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2012-07-18 20:13:58 +00:00

105 lines
2.6 KiB
Fortran

!subroutine genms(msg28,samfac,iwave,cwave,isrch,nwave)
subroutine genmsk(msg28,iwave,nwave)
! Generate a JTMS wavefile.
parameter (NMAX=30*48000) !Max length of wave file
integer*2 iwave(NMAX) !Generated wave file
complex cwave(NMAX) !Alternative for searchms
character*28 msg28 !User message
character*29 msg
character cc*64
integer sent(203)
real*8 dt,phi,f,f0,dfgen,dphi,twopi,foffset,samfac
integer np(9)
data np/5,7,9,11,13,17,19,23,29/ !Permissible message lengths
! 1 2 3 4 5 6
! 0123456789012345678901234567890123456789012345678901234567890123
data cc/'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ./?- _ @'/
!###
samfac=1.d0
isrch=0
!###
msg=msg28//' ' !Extend to 29 characters
do i=28,1,-1 !Find user's message length
if(msg(i:i).ne.' ') go to 1
enddo
1 iz=i+1 !Add one for space at EOM
msglen=iz
if(isrch.ne.0) go to 3
do i=1,9
if(np(i).ge.iz) go to 2
enddo
i=8
2 msglen=np(i)
! Convert message to a bit sequence, 7 bits per character (6 + odd parity)
! Use odd parity because then code 44 (from a 0-63 range) is the 7-bit
! Barker code.
3 sent=0
k=0
do j=1,msglen
if(msg(j:j).eq.' ') then
i=1 + 44
go to 5
else
do i=1,64
if(msg(j:j).eq.cc(i:i)) go to 5
enddo
endif
5 m=0
do n=5,0,-1 !Each character gets 6 bits
k=k+1
sent(k)=iand(1,ishft(i-1,-n))
m=m+sent(k)
enddo
k=k+1
sent(k) = 1 - iand(m,1) !Insert odd parity bit
enddo
nsym=k
! Set up necessary constants
twopi=8.d0*atan(1.d0)
nsps=24
dt=1.d0/(samfac*48000.d0)
f0=48000.d0/nsps
dfgen=0.5d0*f0
foffset=1500.d0 - f0
t=0.d0
k=0
phi=0.d0
nrpt=NMAX/(nsym*nsps)
if(isrch.ne.0) nrpt=1
do irpt=1,nrpt
do j=1,nsym
if(sent(j).eq.1) then
f=f0 + 0.5d0*dfgen + foffset
else
f=f0 - 0.5d0*dfgen + foffset
endif
dphi=twopi*f*dt
do i=1,nsps
k=k+1
phi=phi+dphi
if(isrch.eq.0) then
iwave(k)=nint(32767.0*sin(phi))
else
cwave(k)=cmplx(cos(phi),sin(phi))
endif
enddo
enddo
enddo
if(isrch.eq.0) iwave(k+1:)=0
nwave=k
! call makepings(iwave,nwave)
! write(71) iwave
! call flush(71)
return
end subroutine genmsk