mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-19 02:22:10 -05:00
126 lines
3.5 KiB
Fortran
126 lines
3.5 KiB
Fortran
program ldpcsim240_74
|
|
|
|
! End-to-end test of the (240,74)/crc24 encoder and decoders.
|
|
|
|
use packjt77
|
|
|
|
parameter(N=240, K=74, M=N-K)
|
|
character*8 arg
|
|
character*37 msg0,msg
|
|
character*77 c77
|
|
character*24 c24
|
|
integer*1 msgbits(74)
|
|
integer*1 apmask(240)
|
|
integer*1 cw(240)
|
|
integer*1 codeword(N),message74(74)
|
|
integer ncrc24
|
|
real rxdata(N),llr(N)
|
|
logical first,unpk77_success
|
|
data first/.true./
|
|
|
|
nargs=iargc()
|
|
if(nargs.ne.5 .and. nargs.ne.6) then
|
|
print*,'Usage: ldpcsim niter ndeep #trials s K [msg]'
|
|
print*,'e.g. ldpcsim240_74 20 5 1000 0.85 64 "K9AN K1JT FN20"'
|
|
print*,'s : if negative, then value is ignored and sigma is calculated from SNR.'
|
|
print*,'niter: is the number of BP iterations.'
|
|
print*,'ndeep: -1 is BP only, ndeep>=0 is OSD order'
|
|
print*,'K :is the number of message+CRC bits and must be in the range [50,74]'
|
|
print*,'WSPR-format message is optional'
|
|
return
|
|
endif
|
|
call getarg(1,arg)
|
|
read(arg,*) max_iterations
|
|
call getarg(2,arg)
|
|
read(arg,*) norder
|
|
call getarg(3,arg)
|
|
read(arg,*) ntrials
|
|
call getarg(4,arg)
|
|
read(arg,*) s
|
|
call getarg(5,arg)
|
|
read(arg,*) Keff
|
|
msg0='K9AN K1JT FN20 '
|
|
if(nargs.eq.6) call getarg(6,msg0)
|
|
call pack77(msg0,i3,n3,c77)
|
|
|
|
rate=real(Keff)/real(N)
|
|
|
|
write(*,*) "code rate: ",rate
|
|
write(*,*) "niter : ",max_iterations
|
|
write(*,*) "norder : ",norder
|
|
write(*,*) "s : ",s
|
|
write(*,*) "K : ",Keff
|
|
|
|
msgbits=0
|
|
read(c77,'(77i1)') msgbits(1:77)
|
|
write(*,*) 'message'
|
|
write(*,'(77i1)') msgbits(1:77)
|
|
|
|
call get_crc24(msgbits,74,ncrc24)
|
|
write(c24,'(b24.24)') ncrc24
|
|
read(c24,'(24i1)') msgbits(51:74)
|
|
write(*,'(24i1)') msgbits(51:74)
|
|
write(*,*) 'message with crc24'
|
|
write(*,'(74i1)') msgbits(1:74)
|
|
call encode240_74(msgbits,codeword)
|
|
call init_random_seed()
|
|
call sgran()
|
|
|
|
write(*,*) 'codeword'
|
|
write(*,'(77i1,1x,24i1,1x,73i1)') codeword
|
|
|
|
write(*,*) "Eb/N0 Es/N0 ngood nundetected sigma symbol error rate"
|
|
do idb = 8,-3,-1
|
|
db=idb/2.0-1.0
|
|
sigma=1/sqrt( 2*rate*(10**(db/10.0)) ) ! to make db represent Eb/No
|
|
! sigma=1/sqrt( 2*(10**(db/10.0)) ) ! db represents Es/No
|
|
ngood=0
|
|
nue=0
|
|
nberr=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
|
|
nberr=nberr+nerr
|
|
|
|
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)
|
|
apmask=0
|
|
dmin=0.0
|
|
maxosd=2
|
|
call decode240_74(llr, Keff, maxosd, norder, apmask, message74, cw, ntype, nharderror, dmin)
|
|
if(nharderror.ge.0) then
|
|
n2err=0
|
|
do i=1,N
|
|
if( cw(i).ne.codeword(i) ) n2err=n2err+1
|
|
enddo
|
|
if(n2err.eq.0) then
|
|
ngood=ngood+1
|
|
else
|
|
nue=nue+1
|
|
endif
|
|
endif
|
|
enddo
|
|
! snr2500=db+10*log10(200.0/116.0/2500.0)
|
|
esn0=db+10*log10(rate)
|
|
pberr=real(nberr)/(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
|
|
|
|
end program ldpcsim240_74
|