mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-29 15:48:38 -05:00
fa45380b51
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@7580 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
139 lines
3.1 KiB
Fortran
139 lines
3.1 KiB
Fortran
program ldpcsim
|
|
|
|
use, intrinsic :: iso_c_binding
|
|
use hashing
|
|
use packjt
|
|
|
|
character*22 msg,msgsent,msgreceived
|
|
character*8 arg
|
|
integer*1, allocatable :: codeword(:), decoded(:), message(:)
|
|
real*8, allocatable :: rxdata(:), rxavgd(:)
|
|
real, allocatable :: llr(:)
|
|
integer ihash
|
|
integer*1 hardbits(32)
|
|
|
|
nargs=iargc()
|
|
if(nargs.ne.4) then
|
|
print*,'Usage: ldpcsim niter navg #trials s '
|
|
print*,'eg: ldpcsim 10 1 1000 0.75'
|
|
return
|
|
endif
|
|
call getarg(1,arg)
|
|
read(arg,*) max_iterations
|
|
call getarg(2,arg)
|
|
read(arg,*) navg
|
|
call getarg(3,arg)
|
|
read(arg,*) ntrials
|
|
call getarg(4,arg)
|
|
read(arg,*) s
|
|
|
|
K=16
|
|
N=32
|
|
!rate=real(K)/real(N)
|
|
! don't count hash bits as data bits
|
|
rate=4.0/real(N)
|
|
write(*,*) "rate: ",rate
|
|
write(*,*) "niter= ",max_iterations,"navg= ",navg," s= ",s
|
|
|
|
allocate ( codeword(N), decoded(K), message(K) )
|
|
allocate ( rxdata(N), rxavgd(N), llr(N) )
|
|
|
|
msg="K1JT K9AN"
|
|
call fmtmsg(msg,iz)
|
|
call hash(msg,22,ihash)
|
|
irpt=14
|
|
ihash=iand(ihash,4095) !12-bit hash
|
|
ig=16*ihash + irpt !4-bit report
|
|
write(*,*) irpt,ihash,ig
|
|
|
|
do i=1,16
|
|
message(i)=iand(1,ishft(ig,1-i))
|
|
enddo
|
|
write(*,'(16i1)') message
|
|
call encode_msk40(message,codeword)
|
|
write(*,'(32i1)') codeword
|
|
call init_random_seed()
|
|
|
|
write(*,*) "Eb/N0 SNR2500 ngood nundetected nbadhash"
|
|
do idb = 0, 30
|
|
db=idb/2.0
|
|
sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
|
|
ngood=0
|
|
nue=0
|
|
nbadhash=0
|
|
|
|
itsum=0
|
|
do itrial=1, ntrials
|
|
rxavgd=0d0
|
|
do iav=1,navg
|
|
call sgran()
|
|
! Create a realization of a noisy received word
|
|
do i=1,N
|
|
rxdata(i) = 2.0*codeword(i)-1.0 + sigma*gran()
|
|
enddo
|
|
rxavgd=rxavgd+rxdata
|
|
enddo
|
|
rxdata=rxavgd
|
|
|
|
! Correct signal normalization is important for this decoder.
|
|
rxav=sum(rxdata)/N
|
|
rx2av=sum(rxdata*rxdata)/N
|
|
rxsig=sqrt(rx2av-rxav*rxav)
|
|
rxdata=rxdata/rxsig
|
|
if( s .le. 0 ) then
|
|
ss=sigma
|
|
else
|
|
ss=s
|
|
endif
|
|
|
|
llr=2.0*rxdata/(ss*ss)
|
|
|
|
call bpdecode40(llr, max_iterations, decoded, niterations)
|
|
! If the decoder finds a valid codeword, niterations will be .ge. 0.
|
|
if( niterations .ge. 0 ) then
|
|
nueflag=0
|
|
nhashflag=0
|
|
imsg=0
|
|
do i=1,16
|
|
imsg=ishft(imsg,1)+iand(1,decoded(17-i))
|
|
enddo
|
|
nrxrpt=iand(imsg,15)
|
|
nrxhash=(imsg-nrxrpt)/16
|
|
if( nrxhash .ne. ihash ) then
|
|
nbadhash=nbadhash+1
|
|
nhashflag=1
|
|
endif
|
|
|
|
! Check the message plus hash against what was sent.
|
|
do i=1,K
|
|
if( message(i) .ne. decoded(i) ) then
|
|
nueflag=1
|
|
endif
|
|
enddo
|
|
|
|
if( nhashflag .eq. 0 .and. nueflag .eq. 0 ) then
|
|
ngood=ngood+1
|
|
itsum=itsum+niterations
|
|
else if( nhashflag .eq. 0 .and. nueflag .eq. 1 ) then
|
|
nue=nue+1;
|
|
endif
|
|
else
|
|
hardbits=0
|
|
where(llr .gt. 0) hardbits=1
|
|
! write(*,'(32i1)') hardbits
|
|
! write(*,'(32i1)') codeword
|
|
isum=0
|
|
do i=1,32
|
|
if( hardbits(i) .ne. codeword(i) ) isum=isum+1
|
|
enddo
|
|
! write(*,*) 'number of errors ',isum
|
|
endif
|
|
enddo
|
|
avits=real(itsum)/real(ngood+0.1)
|
|
snr2500=db-10.0
|
|
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,1x,i8,1x,f8.2,1x,f8.1)") db,snr2500,ngood,nue,nbadhash,ss,avits
|
|
|
|
enddo
|
|
|
|
end program ldpcsim
|