mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-01 08:07:10 -04:00
15c46c8ae8
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7648 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
146 lines
5.2 KiB
Fortran
146 lines
5.2 KiB
Fortran
program fsk4hf
|
|
|
|
! Simulate characteristics of a potential mode using LDPC (168,84) code,
|
|
! 4-FSK modulation, and 30 s T/R sequences.
|
|
|
|
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 (3760)
|
|
|
|
character*8 arg
|
|
complex c0(0:NZ-1) !Complex waveform
|
|
complex c(0:NZ-1) !Complex waveform
|
|
real xnoise(0:NZ-1) !Generated random noise
|
|
real ynoise(0:NZ-1) !Generated random noise
|
|
real rxdata(2*ND),llr(2*ND) !Soft symbols
|
|
real s(0:NSPS,NN)
|
|
real savg(0:NSPS)
|
|
real ps(0:3)
|
|
integer id(ND) !Symbol values (0-3), data only
|
|
integer id1(ND) !Recovered data values
|
|
integer*1 msgbits(KK),decoded(KK),apmask(ND),cw(ND)
|
|
data msgbits/0,0,1,0,0,1,1,1,1,0,0,1,0,0,0,0,0,0,0,0,1,0,0,0,1,1,0,0,0,1, &
|
|
1,1,1,0,1,1,1,1,1,1,1,0,0,1,0,0,1,1,0,1,0,1,1,1,0,1,1,0,1,1, &
|
|
1,1,0,1,0,1,1,0,0,0,0,0,1,0,0,0,0,0,1,0,1,0,1,0/
|
|
|
|
nargs=iargc()
|
|
if(nargs.ne.5) then
|
|
print*,'Usage: fsk4hf f0(Hz) delay(ms) fspread(Hz) iters snr(dB)'
|
|
print*,'Example: fsk4hf 20 0 0 10 -20'
|
|
print*,'Set snr=0 to cycle through a range'
|
|
go to 999
|
|
endif
|
|
call getarg(1,arg)
|
|
read(arg,*) f0 !Generated carrier frequency
|
|
call getarg(2,arg)
|
|
read(arg,*) delay !Delta_t (ms) for Watterson model
|
|
call getarg(3,arg)
|
|
read(arg,*) fspread !Fspread (Hz) for Watterson model
|
|
call getarg(4,arg)
|
|
read(arg,*) iters !Iterations at each SNR
|
|
call getarg(5,arg)
|
|
read(arg,*) snrdb !Specified SNR_2500
|
|
|
|
twopi=8.0*atan(1.0)
|
|
fs=12000.0/84.0 !Sample rate = 142.857... Hz
|
|
dt=1.0/fs !Sample interval (s)
|
|
tt=NSPS*dt !Duration of "itone" symbols (s)
|
|
baud=1.0/tt !Keying rate for "itone" symbols (baud)
|
|
txt=NZ*dt !Transmission length (s)
|
|
bandwidth_ratio=2500.0/(fs/2.0)
|
|
write(*,1000) f0,delay,fspread,iters,baud,4*baud,txt
|
|
1000 format('f0:',f5.1,' Delay:',f4.1,' fSpread:',f5.2, &
|
|
' Iters:',i6/'Baud:',f7.3,' BW:',f5.1,' TxT:',f5.1,f5.2/)
|
|
write(*,1004)
|
|
1004 format(/' SNR sym bit ser ber fer fsigma'/50('-'))
|
|
|
|
call genfsk4hf(msgbits,f0,id,c0) !Generate baseband waveform
|
|
isna=-10
|
|
isnb=-30
|
|
if(snrdb.ne.0.0) then
|
|
isna=nint(snrdb)
|
|
isnb=isna
|
|
endif
|
|
do isnr=isna,isnb,-1 !Loop over SNR range
|
|
snrdb=isnr
|
|
sig=sqrt(bandwidth_ratio) * 10.0**(0.05*snrdb)
|
|
if(snrdb.gt.90.0) sig=1.0
|
|
nhard=0
|
|
nbit=0
|
|
nfe=0
|
|
sqf=0.
|
|
do iter=1,iters !Loop over requested iterations
|
|
c=c0
|
|
if(delay.ne.0.0 .or. fspread.ne.0.0) then
|
|
call watterson(c,NZ,fs,delay,fspread)
|
|
endif
|
|
c=sig*c !Scale to requested SNR
|
|
if(snrdb.lt.90) then
|
|
do i=0,NZ-1 !Generate gaussian noise
|
|
xnoise(i)=gran()
|
|
ynoise(i)=gran()
|
|
enddo
|
|
c=c + cmplx(xnoise,ynoise) !Add AWGN noise
|
|
endif
|
|
df=fs/(2*NSPS)
|
|
i0=nint(f0/df)
|
|
call spec4(c,s,savg)
|
|
do i=0,NSPS
|
|
write(12,3001) i*df,savg(i),db(savg(i))
|
|
3001 format(3f15.3)
|
|
enddo
|
|
|
|
do j=1,ND
|
|
nlo=0
|
|
nhi=0
|
|
k=j+5
|
|
if(j.ge.43) k=j+9
|
|
ps=s(i0:i0+6:2,k)
|
|
ps=sqrt(ps) !###
|
|
rlo=max(ps(1),ps(3))-max(ps(0),ps(2))
|
|
rhi=max(ps(2),ps(3))-max(ps(0),ps(1))
|
|
if(rlo.ge.0.0) nlo=1
|
|
if(rhi.ge.0.0) nhi=1
|
|
rxdata(2*j-1)=rhi
|
|
rxdata(2*j)=rlo
|
|
id1(j)=2*nhi+nlo
|
|
enddo
|
|
! write(*,1001) id(1:70)
|
|
! write(*,1001) id1(1:70)
|
|
!1001 format(70i1)
|
|
nhard=nhard+count(id.ne.id1)
|
|
nbit=nbit + count(iand(id,1).ne.iand(id1,1)) + &
|
|
count(iand(id,2).ne.iand(id1,2))
|
|
|
|
rxav=sum(rxdata)/ND
|
|
rx2av=sum(rxdata*rxdata)/ND
|
|
rxsig=sqrt(rx2av-rxav*rxav)
|
|
rxdata=rxdata/rxsig
|
|
ss=0.84
|
|
llr=2.0*rxdata/(ss*ss)
|
|
apmask=0
|
|
max_iterations=40
|
|
ifer=0
|
|
call bpdecode168(llr,apmask,max_iterations,decoded,niterations,cw)
|
|
nbadcrc=0
|
|
if(niterations.ge.0) call chkcrc12(decoded,nbadcrc)
|
|
if(niterations.lt.0 .or. count(msgbits.ne.decoded).gt.0 .or. &
|
|
nbadcrc.ne.0) ifer=1
|
|
nfe=nfe+ifer
|
|
enddo
|
|
|
|
fsigma=sqrt(sqf/iters)
|
|
ser=float(nhard)/(ND*iters)
|
|
ber=float(nbit)/(2*ND*iters)
|
|
fer=float(nfe)/iters
|
|
write(*,1050) snrdb,nhard,nbit,ser,ber,fer,fsigma
|
|
! write(60,1050) snrdb,nhard,ber,fer,fsigma
|
|
1050 format(f6.1,2i6,2f8.4,f7.3,f8.2)
|
|
enddo
|
|
|
|
999 end program fsk4hf
|