mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-09-17 10:46:33 -04:00
67 lines
1.8 KiB
Fortran
67 lines
1.8 KiB
Fortran
subroutine ft2_iwave(msg37,f0,snrdb,iwave)
|
|
|
|
! Generate waveform for experimental "FT2" mode
|
|
|
|
use packjt77
|
|
include 'ft2_params.f90' !Set various constants
|
|
parameter (NWAVE=NN*NSPS)
|
|
character msg37*37,msgsent37*37
|
|
real wave(NMAX)
|
|
integer itone(NN)
|
|
integer*2 iwave(NMAX) !Generated full-length waveform
|
|
|
|
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
|
|
|
|
! Source-encode, then get itone():
|
|
itype=1
|
|
call genft2(msg37,0,msgsent37,itone,itype)
|
|
|
|
k=0
|
|
phi=0.0
|
|
do j=1,NN !Generate real waveform
|
|
dphi=twopi*(f0*dt+(hmod/2.0)*(2*itone(j)-1)/real(NSPS))
|
|
do i=1,NSPS
|
|
k=k+1
|
|
wave(k)=sig*sin(phi)
|
|
phi=mod(phi+dphi,twopi)
|
|
enddo
|
|
enddo
|
|
kz=k
|
|
|
|
peak=maxval(abs(wave(1:kz)))
|
|
! nslots=1
|
|
! if(width.gt.0.0) call filt8(f0,nslots,width,wave)
|
|
|
|
if(snrdb.lt.90) then
|
|
do i=1,NMAX !Add gaussian noise at specified SNR
|
|
xnoise=gran()
|
|
wave(i)=wave(i) + xnoise
|
|
enddo
|
|
endif
|
|
|
|
gain=1.0
|
|
if(snrdb.lt.90.0) then
|
|
wave=gain*wave
|
|
else
|
|
datpk=maxval(abs(wave))
|
|
fac=32767.0/datpk
|
|
wave=fac*wave
|
|
endif
|
|
|
|
if(any(abs(wave).gt.32767.0)) print*,"Warning - data will be clipped."
|
|
iwave(1:kz)=nint(wave(1:kz))
|
|
|
|
return
|
|
end subroutine ft2_iwave
|