WSJT-X/libm65/genqra64a.f90

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subroutine genqra64a(msg0,ichk,ntxfreq,mode64,itype,msgsent,iwave,nwave)
! Encodes a QRA64 message to yield itone(1:84)
use packjt
parameter (NMAX=2*60*11025)
character*22 msg0
character*22 message !Message to be generated
character*22 msgsent !Message as it will be received
integer itone(84)
character*3 cok !' ' or 'OOO'
real*8 t,dt,phi,f,f0,dfgen,dphi,twopi,samfac,tsym
integer dgen(13)
integer sent(63)
integer*2 iwave(NMAX)
integer icos7(0:6)
data icos7/2,5,6,0,4,1,3/ !Defines a 7x7 Costas array
data twopi/6.283185307179586476d0/
save
if(msg0(1:1).eq.'@') then
read(msg0(2:5),*,end=1,err=1) nfreq
go to 2
1 nfreq=1000
2 itone(1)=nfreq
write(msgsent,1000) nfreq
1000 format(i5,' Hz')
else
message=msg0
do i=1,22
if(ichar(message(i:i)).eq.0) then
message(i:)=' '
exit
endif
enddo
do i=1,22 !Strip leading blanks
if(message(1:1).ne.' ') exit
message=message(i+1:)
enddo
call chkmsg(message,cok,nspecial,flip)
call packmsg(message,dgen,itype) !Pack message into 72 bits
call unpackmsg(dgen,msgsent) !Unpack to get message sent
if(ichk.ne.0) go to 999 !Return if checking only
call qra64_enc(dgen,sent) !Encode using QRA64
nsync=10
itone(1:7)=nsync*icos7 !Insert 7x7 Costas array in 3 places
itone(8:39)=sent(1:32)
itone(40:46)=nsync*icos7
itone(47:77)=sent(33:63)
itone(78:84)=nsync*icos7
endif
! Set up necessary constants
nsym=84
tsym=6912.d0/12000.d0
samfac=1.d0
dt=1.d0/(samfac*11025.d0)
f0=ntxfreq
ndf=2**(mode64-1)
dfgen=ndf*12000.d0/6912.d0
phi=0.d0
dphi=twopi*dt*f0
i=0
iz=84*6912*11025.d0/12000.d0
t=0.d0
j0=0
do i=1,iz
t=t+dt
j=t/tsym
if(j.ne.j0) then
f=f0 + itone(j)*dfgen
dphi=twopi*dt*f
j0=j
endif
phi=phi+dphi
if(phi.gt.twopi) phi=phi-twopi
xphi=phi
iwave(2*i-1)=32767.0*cos(xphi)
iwave(2*i)=32767.0*sin(xphi)
enddo
nwave=2*iz
999 return
end subroutine genqra64a