mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-10-31 15:47:10 -04:00
135 lines
3.8 KiB
Fortran
135 lines
3.8 KiB
Fortran
program ldpcsim174_91
|
|
! End to end test of the (174,91)/crc14 encoder and decoder.
|
|
use packjt77
|
|
|
|
integer, parameter:: N=174, K=91, M=N-K
|
|
character*37 msg,msgsent,msgreceived
|
|
character*77 c77
|
|
character*8 arg
|
|
character*6 grid
|
|
character*96 tmpchar
|
|
integer*1, allocatable :: codeword(:), decoded(:), message(:)
|
|
integer*1 msgbits(77)
|
|
integer*1 message77(77),message91(91)
|
|
integer*1 apmask(N), cw(N)
|
|
integer nerrtot(0:N),nerrdec(0:N)
|
|
logical unpk77_success
|
|
real*8, allocatable :: rxdata(:)
|
|
real, allocatable :: llr(:)
|
|
|
|
nerrtot=0
|
|
nerrdec=0
|
|
|
|
nargs=iargc()
|
|
if(nargs.ne.6) then
|
|
print*,'Usage: ldpcsim niter ndepth #trials s Keff nbposd'
|
|
print*,'eg: ldpcsim 10 2 1000 0.84 91 1'
|
|
print*,'niter: max BP iterations'
|
|
print*,'ndepth: OSD order'
|
|
print*,'s: noise sigma; if negative value is ignored and sigma is calculated from SNR.'
|
|
print*,'nbposd=0, no coupling. nbposd>0, maxsuper=nbposd; nbposd<0, no OSD'
|
|
return
|
|
endif
|
|
call getarg(1,arg)
|
|
read(arg,*) max_iterations
|
|
call getarg(2,arg)
|
|
read(arg,*) ndepth
|
|
call getarg(3,arg)
|
|
read(arg,*) ntrials
|
|
call getarg(4,arg)
|
|
read(arg,*) s
|
|
call getarg(5,arg)
|
|
read(arg,*) Keff
|
|
call getarg(6,arg)
|
|
read(arg,*) nbposd
|
|
|
|
! scale Eb/No for a (174,91) code
|
|
rate=real(K)/real(N)
|
|
|
|
write(*,*) "rate: ",rate
|
|
write(*,*) "niter= ",max_iterations," s= ",s
|
|
|
|
allocate ( codeword(N), decoded(K), message(K) )
|
|
allocate ( rxdata(N), llr(N) )
|
|
|
|
msg="K9ABC K1ABC FN20"
|
|
i3=0
|
|
n3=1
|
|
call pack77(msg,i3,n3,c77) !Pack into 12 6-bit bytes
|
|
call unpack77(c77,1,msgsent,unpk77_success) !Unpack to get msgsent
|
|
write(*,*) "message sent ",msgsent
|
|
|
|
read(c77,'(77i1)') msgbits(1:77)
|
|
write(*,*) 'message'
|
|
write(*,'(a71,1x,a3,1x,a3)') c77(1:71),c77(72:74),c77(75:77)
|
|
|
|
call init_random_seed()
|
|
|
|
call encode174_91(msgbits,codeword)
|
|
write(*,*) 'crc14'
|
|
write(*,'(14i1)') codeword(78:91)
|
|
write(*,*) 'codeword'
|
|
write(*,'(22(8i1,1x))') codeword
|
|
|
|
write(*,*) "Eb/N0 Es/N0 ngood nundetected sigma psymerr"
|
|
do idb = 10,-4,-1
|
|
db=idb/2.0-1.0
|
|
sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
|
|
ngood=0
|
|
nue=0
|
|
nsumerr=0
|
|
|
|
do itrial=1, ntrials
|
|
! Create a realization of a noisy received word
|
|
do i=1,N
|
|
rxdata(i) = 2.0*codeword(i)-1.0 + sigma*gran()
|
|
enddo
|
|
nerr=0
|
|
do i=1,N
|
|
if( rxdata(i)*(2*codeword(i)-1.0) .lt. 0 ) nerr=nerr+1
|
|
enddo
|
|
if(nerr.ge.1) nerrtot(nerr)=nerrtot(nerr)+1
|
|
|
|
rxav=sum(rxdata)/N
|
|
rx2av=sum(rxdata*rxdata)/N
|
|
rxsig=sqrt(rx2av-rxav*rxav)
|
|
rxdata=rxdata/rxsig
|
|
if( s .lt. 0 ) then
|
|
ss=sigma
|
|
else
|
|
ss=s
|
|
endif
|
|
|
|
llr=2.0*rxdata/(ss*ss)
|
|
nap=0 ! number of AP bits
|
|
llr(1:nap)=5*(2.0*msgbits(1:nap)-1.0)
|
|
apmask=0
|
|
apmask(1:nap)=1
|
|
call decode174_91(llr,Keff,nbposd,ndepth,apmask,message91,cw,ntype,nharderrors,dmin)
|
|
! If the decoder finds a valid codeword, nharderrors will be .ge. 0.
|
|
if( nharderrors.ge.0 ) then
|
|
nhw=count(cw.ne.codeword)
|
|
if(nhw.eq.0) then ! this is a good decode
|
|
ngood=ngood+1
|
|
nerrdec(nerr)=nerrdec(nerr)+1
|
|
else
|
|
nue=nue+1
|
|
endif
|
|
endif
|
|
nsumerr=nsumerr+nerr
|
|
enddo
|
|
|
|
esn0=db+10.0*log10(rate)
|
|
pberr=real(nsumerr)/(real(ntrials*N))
|
|
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,8x,f5.2,8x,e10.3)") db,esn0,ngood,nue,ss,pberr
|
|
|
|
enddo
|
|
|
|
open(unit=23,file='nerrhisto.dat',status='unknown')
|
|
do i=1,174
|
|
write(23,'(i4,2x,i10,i10,f10.2)') i,nerrdec(i),nerrtot(i),real(nerrdec(i))/real(nerrtot(i)+1e-10)
|
|
enddo
|
|
close(23)
|
|
|
|
end program ldpcsim174_91
|