From 1cc1fa015b44eac8d6c48cad8e806204b6ca818d Mon Sep 17 00:00:00 2001 From: Steven Franke Date: Thu, 4 Aug 2016 00:46:57 +0000 Subject: [PATCH] Reconfigure simulator for short message tests. git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6993 ab8295b8-cf94-4d9e-aec4-7959e3be5d79 --- lib/ldpcsim.f90 | 117 +++++++++++++----------------------------------- 1 file changed, 30 insertions(+), 87 deletions(-) diff --git a/lib/ldpcsim.f90 b/lib/ldpcsim.f90 index 1904ed197..1e08a7714 100644 --- a/lib/ldpcsim.f90 +++ b/lib/ldpcsim.f90 @@ -1,29 +1,21 @@ program ldpcsim -! simulate with packed 72-bit messages and 8-bit hash - so only makes -! sense to use this with codes having K=80. - use, intrinsic :: iso_c_binding use hashing use packjt character*22 msg,msgsent,msgreceived -integer*4 i4Msg6BitWords(12),i4Dec6BitWords(12) -integer*1, target:: i1Msg8BitBytes(10) ! 72 bit msg + 8 bit hash -integer*1, target:: i1Dec8BitBytes(10) ! 72 bit msg + 8 bit hash -integer*1 i1hashdec character*80 prefix character*85 pchk_file,gen_file character*8 arg integer*1, allocatable :: codeword(:), decoded(:), message(:) real*8, allocatable :: lratio(:), rxdata(:) -integer*1 i1hash(4),i1 -equivalence (ihash,i1hash) +integer ihash nargs=iargc() if(nargs.ne.7) then print*,'Usage: ldpcsim N K niter ndither #trials s ' - print*,'eg: ldpcsim "/pathto/128-80-peg-reg3" 128 80 10 1 1000 0.75' + print*,'eg: ldpcsim "/pathto/peg-32-16-reg3" 32 16 10 1 1000 0.75' return endif call getarg(1,prefix) @@ -43,9 +35,10 @@ read(arg,*) s pchk_file=trim(prefix)//".pchk" gen_file=trim(prefix)//".gen" -! rate=real(K)/real(N) +rate=real(K)/real(N) +write(*,*) "rate: ",rate ! don't count hash bits as data bits -rate=72.0/real(N) +!rate=5.0/real(N) write(*,*) "pchk file: ",pchk_file write(*,*) "niter= ",max_iterations," ndither= ",max_dither," s= ",s @@ -54,59 +47,34 @@ allocate ( codeword(N), decoded(K), message(K) ) allocate ( lratio(N), rxdata(N) ) call init_ldpc(trim(pchk_file)//char(0),trim(gen_file)//char(0)) -msg="123" -call fmtmsg(msg,iz) -call packmsg(msg,i4Msg6BitWords,itype) -call unpackmsg(i4Msg6BitWords,msgsent) -write(*,*) "Message: ",msgsent +msg="K9AN K1JT RRR" +irpt=62 +call hash(msg,22,ihash) +ihash=iand(ihash,1023) !10-bit hash +ig=64*ihash + irpt !6-bit report +write(*,*) irpt,ihash,ig -! Convert from 12 6-bit words to 10 8-bit words -i4=0 -ik=0 -im=0 -do i=1,12 - nn=i4Msg6BitWords(i) - do j=1, 6 - ik=ik+1 - i4=i4+i4+iand(1,ishft(nn,j-6)) - i4=iand(i4,255) - if(ik.eq.8) then - im=im+1 -! if(i4.gt.127) i4=i4-256 - i1Msg8BitBytes(im)=i4 - ik=0 - endif - enddo +do i=1,16 + message(i)=iand(1,ishft(ig,1-i)) enddo -ihash=nhash(c_loc(i1Msg8BitBytes),int(9,c_size_t),146) -ihash=2*iand(ihash,255) -i1Msg8BitBytes(10)=i1hash(1) - -mbit=0 -do i=1, 10 - i1=i1Msg8BitBytes(i) - do ibit=1,8 - mbit=mbit+1 - message(mbit)=iand(1,ishft(i1,ibit-8)) - enddo -enddo call ldpc_encode(message,codeword) +call init_random_seed() write(*,*) "Eb/N0 ngood nundetected nbadhash" -do idb = 0, 11 - db=idb/2.0-0.5 +do idb = -6, 14 + db=idb/2.0-1.0 sigma=1/sqrt( 2*rate*(10**(db/10.0)) ) - ngood=0 nue=0 nbadhash=0 do itrial=1, ntrials - +call sgran() ! Create a realization of a noisy received word do i=1,N rxdata(i) = 2.0*(codeword(i)-0.5) + sigma*gran() +!write(*,*) i,gran() enddo ! Correct signal normalization is important for this decoder. @@ -114,45 +82,35 @@ do idb = 0, 11 rx2av=sum(rxdata*rxdata)/N rxsig=sqrt(rx2av-rxav*rxav) rxdata=rxdata/rxsig - ! To match the metric to the channel, s should be set to the noise standard deviation. ! For now, set s to the value that optimizes decode probability near threshold. ! The s parameter can be tuned to trade a few tenth's dB of threshold for an order of ! magnitude in UER + if( s .le. 0 ) then + ss=sigma + else + ss=s + endif + do i=1,N - if( s .le. 0 ) then - ss=sigma - else - ss=s - endif lratio(i)=exp(2.0*rxdata(i)/(ss*ss)) enddo ! max_iterations is max number of belief propagation iterations call ldpc_decode(lratio, decoded, max_iterations, niterations, max_dither, ndither) - ! If the decoder finds a valid codeword, niterations will be .ge. 0. if( niterations .ge. 0 ) then nueflag=0 nhashflag=0 -! The decoder found a codeword. Compare received hash (byte 10) with computed hash. -! Collapse 80 decoded bits to 10 bytes. Bytes 1-9 are the message, byte 10 is the hash. - do ibyte=1,10 - itmp=0 - do ibit=1,8 - itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*8+ibit)) - enddo - i1Dec8BitBytes(ibyte)=itmp + imsg=0 + do i=1,16 + imsg=ishft(imsg,1)+iand(1,decoded(17-i)) enddo + nrxrpt=iand(imsg,63) + nrxhash=(imsg-nrxrpt)/64 -! Calculate the hash using the first 9 bytes. - ihashdec=nhash(c_loc(i1Dec8BitBytes),int(9,c_size_t),146) - ihashdec=2*iand(ihashdec,255) - -! Compare calculated hash with received byte 10 - if they agree, keep the message. - i1hashdec=ihashdec - if( i1hashdec .ne. i1Dec8BitBytes(10) ) then + if( nrxhash .ne. ihash ) then nbadhash=nbadhash+1 nhashflag=1 endif @@ -166,21 +124,6 @@ do idb = 0, 11 if( nhashflag .eq. 0 .and. nueflag .eq. 0 ) then ngood=ngood+1 - -! don't bother to unpack while testing -if( .false. ) then -! unpack 72-bit message - do ibyte=1,12 - itmp=0 - do ibit=1,6 - itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit)) - enddo - i4Dec6BitWords(ibyte)=itmp - enddo - call unpackmsg(i4Dec6BitWords,msgreceived) - print*,"Received ",msgreceived -endif - else if( nhashflag .eq. 0 .and. nueflag .eq. 1 ) then nue=nue+1; endif