52 lines
1.7 KiB
Fortran
52 lines
1.7 KiB
Fortran
subroutine genfsk4hf(msgbits,f0,id,c)
|
|
|
|
parameter (KK=84) !Information bits (72 + CRC12)
|
|
parameter (ND=84) !Data symbols: LDPC (168,84), r=1/2
|
|
parameter (NS=12) !Sync symbols (3 @ 4x4 Costas arrays)
|
|
parameter (NR=2) !Ramp up/down
|
|
parameter (NN=NR+NS+ND) !Total symbols (98)
|
|
parameter (NSPS=2688/84) !Samples per symbol (32)
|
|
parameter (NZ=NSPS*NN) !Samples in baseband waveform (3136)
|
|
|
|
complex c(0:NZ-1) !Complex waveform
|
|
integer id0(NN) !2-bit data (values 0-3), all symbols
|
|
integer id(ND) !2-bit data (values 0-3), data only
|
|
integer*1 msgbits(KK),codeword(2*ND)
|
|
integer icos4(4) !4x4 Costas array
|
|
data icos4/0,1,3,2/
|
|
|
|
twopi=8.0*atan(1.0)
|
|
fs=12000.0/84.0
|
|
dt=1.0/fs
|
|
baud=1.0/(NSPS*dt)
|
|
call encode168(msgbits,codeword) !Encode the test message
|
|
id0(1)=0 !Ramp-up
|
|
id0(2:5)=icos4 !First Costas array
|
|
id0(48:51)=icos4 !Second
|
|
id0(94:97)=icos4 !Third
|
|
id0(98)=0 !Ramp down
|
|
j=5
|
|
do i=1,84 !Data symbols
|
|
id(i)=2*codeword(2*i-1) + codeword(2*i)
|
|
j=j+1
|
|
if(i.eq.43) j=j+4
|
|
id0(j)=id(i)
|
|
enddo
|
|
|
|
! Generate the 4-FSK waveform, low tone at f=0
|
|
c=0.
|
|
phi=0.d0
|
|
k=-1
|
|
do j=1,NN
|
|
dphi=twopi*(f0+id0(j)*baud)*dt
|
|
do i=1,NSPS
|
|
k=k+1
|
|
phi=phi+dphi
|
|
if(phi.gt.twopi) phi=phi-twopi
|
|
c(k)=cmplx(cos(phi),sin(phi))
|
|
enddo
|
|
enddo
|
|
|
|
return
|
|
end subroutine genfsk4hf
|