mirror of https://github.com/saitohirga/WSJT-X.git
Working toward whole-hog switchover to new LDPC code with 77 bit messages in MSK144.
This commit is contained in:
Steve Franke
parent
42f75bf404
commit
622ed4a3ab
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@ -8,18 +8,18 @@ subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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integer*1 cw(N),apmask(N)
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integer*1 decoded(K)
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integer*1 message77(77)
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integer Nm(12,M)
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integer Mn(4,N)
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integer nrw(M),ncw(N)
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integer Nm(11,M)
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integer Mn(3,N)
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integer nrw(M)
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integer synd(M)
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real tov(4,N)
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real toc(12,M)
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real tanhtoc(12,M)
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real toc(11,M)
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real tanhtoc(11,M)
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real zn(N)
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real llr(N)
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real Tmn
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include "ldpc_128_90_b_reordered_parity.f90"
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include "ldpc_128_90_reordered_parity.f90"
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decoded=0
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toc=0
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@ -39,7 +39,7 @@ subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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! Update bit log likelihood ratios (tov=0 in iteration 0).
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do i=1,N
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if( apmask(i) .ne. 1 ) then
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zn(i)=llr(i)+sum(tov(1:ncw(i),i))
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zn(i)=llr(i)+sum(tov(1:ncw,i))
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else
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zn(i)=llr(i)
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endif
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@ -74,7 +74,7 @@ subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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ncnt=ncnt+1
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endif
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! write(*,*) iter,ncheck,nd,ncnt
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if( ncnt .ge. 5 .and. iter .ge. 10 .and. ncheck .gt. 15) then
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if( ncnt .ge. 3 .and. iter .ge. 5 .and. ncheck .gt. 10) then
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nharderror=-1
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return
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endif
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@ -86,7 +86,7 @@ subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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do i=1,nrw(j)
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ibj=Nm(i,j)
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toc(i,j)=zn(ibj)
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do kk=1,4 ! subtract off what the bit had received from the check
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do kk=1,ncw ! subtract off what the bit had received from the check
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if( Mn(kk,ibj) .eq. j ) then
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toc(i,j)=toc(i,j)-tov(kk,ibj)
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endif
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@ -96,11 +96,11 @@ subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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! send messages from check nodes to variable nodes
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do i=1,M
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tanhtoc(1:12,i)=tanh(-toc(1:12,i)/2)
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tanhtoc(1:11,i)=tanh(-toc(1:11,i)/2)
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enddo
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do j=1,N
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do i=1,ncw(j)
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do i=1,ncw
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ichk=Mn(i,j) ! Mn(:,j) are the checks that include bit j
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Tmn=product(tanhtoc(1:nrw(ichk),ichk),mask=Nm(1:nrw(ichk),ichk).ne.j)
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call platanh(-Tmn,y)
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@ -0,0 +1,116 @@
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subroutine bpdecode128_90(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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!
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! A log-domain belief propagation decoder for the (128,90) code.
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!
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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integer, parameter:: N=128, K=90, M=N-K
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integer*1 cw(N),apmask(N)
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integer*1 decoded(K)
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integer*1 message77(77)
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integer Nm(12,M)
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integer Mn(4,N)
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integer nrw(M),ncw(N)
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integer synd(M)
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real tov(4,N)
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real toc(12,M)
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real tanhtoc(12,M)
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real zn(N)
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real llr(N)
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real Tmn
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include "ldpc_128_90_b_reordered_parity.f90"
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decoded=0
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toc=0
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tov=0
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tanhtoc=0
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! initialize messages to checks
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do j=1,M
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do i=1,nrw(j)
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toc(i,j)=llr((Nm(i,j)))
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enddo
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enddo
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ncnt=0
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do iter=0,maxiterations
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! Update bit log likelihood ratios (tov=0 in iteration 0).
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do i=1,N
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if( apmask(i) .ne. 1 ) then
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zn(i)=llr(i)+sum(tov(1:ncw(i),i))
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else
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zn(i)=llr(i)
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endif
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enddo
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! Check to see if we have a codeword (check before we do any iteration).
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cw=0
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where( zn .gt. 0. ) cw=1
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ncheck=0
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do i=1,M
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synd(i)=sum(cw(Nm(1:nrw(i),i)))
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if( mod(synd(i),2) .ne. 0 ) ncheck=ncheck+1
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! if( mod(synd(i),2) .ne. 0 ) write(*,*) 'check ',i,' unsatisfied'
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enddo
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! write(*,*) 'number of unsatisfied parity checks ',ncheck
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if( ncheck .eq. 0 ) then ! we have a codeword - reorder the columns and return it
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decoded=cw(1:K)
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call chkcrc13a(decoded,nbadcrc)
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if(nbadcrc.eq.0) then
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message77=decoded(1:77)
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nharderror=count( (2*cw-1)*llr .lt. 0.0 )
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return
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endif
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endif
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if( iter.gt.0 ) then ! this code block implements an early stopping criterion
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! if( iter.gt.10000 ) then ! this code block implements an early stopping criterion
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nd=ncheck-nclast
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if( nd .lt. 0 ) then ! # of unsatisfied parity checks decreased
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ncnt=0 ! reset counter
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else
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ncnt=ncnt+1
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endif
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! write(*,*) iter,ncheck,nd,ncnt
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if( ncnt .ge. 3 .and. iter .ge. 5 .and. ncheck .gt. 10) then
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nharderror=-1
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return
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endif
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endif
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nclast=ncheck
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! Send messages from bits to check nodes
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do j=1,M
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do i=1,nrw(j)
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ibj=Nm(i,j)
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toc(i,j)=zn(ibj)
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do kk=1,4 ! subtract off what the bit had received from the check
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if( Mn(kk,ibj) .eq. j ) then
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toc(i,j)=toc(i,j)-tov(kk,ibj)
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endif
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enddo
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enddo
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enddo
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! send messages from check nodes to variable nodes
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do i=1,M
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tanhtoc(1:12,i)=tanh(-toc(1:12,i)/2)
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enddo
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do j=1,N
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do i=1,ncw(j)
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ichk=Mn(i,j) ! Mn(:,j) are the checks that include bit j
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Tmn=product(tanhtoc(1:nrw(ichk),ichk),mask=Nm(1:nrw(ichk),ichk).ne.j)
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call platanh(-Tmn,y)
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! y=atanh(-Tmn)
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tov(i,j)=2*y
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enddo
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enddo
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enddo
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nharderror=-1
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return
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end subroutine bpdecode128_90
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@ -0,0 +1,58 @@
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subroutine encode_128_90(message77,codeword)
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!
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! Add a 13-bit CRC to a 77-bit message and return a 128-bit codeword
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!
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use, intrinsic :: iso_c_binding
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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integer, parameter:: N=128, K=90, M=N-K
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character*90 tmpchar
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integer*1 codeword(N)
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integer*1 gen(M,K)
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integer*1 message77(77),message(K)
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integer*1 pchecks(M)
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integer*1, target :: i1MsgBytes(12)
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include "ldpc_128_90_generator.f90"
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logical first
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data first/.true./
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save first,gen
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if( first ) then ! fill the generator matrix
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gen=0
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do i=1,M
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do j=1,23
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read(g(i)(j:j),"(Z1)") istr
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ibmax=4
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if(j.eq.23) ibmax=2
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do jj=1, ibmax
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icol=(j-1)*4+jj
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if( btest(istr,4-jj) ) gen(i,icol)=1
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enddo
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enddo
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enddo
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first=.false.
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endif
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! Add 13 bit CRC to form 90-bit message+CRC13
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write(tmpchar,'(77i1)') message77
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tmpchar(78:80)='000'
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i1MsgBytes=0
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read(tmpchar,'(10b8)') i1MsgBytes(1:10)
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ncrc13 = crc13 (c_loc (i1MsgBytes), 12)
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write(tmpchar(78:90),'(b13)') ncrc13
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read(tmpchar,'(90i1)') message
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do i=1,M
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nsum=0
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do j=1,K
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nsum=nsum+message(j)*gen(i,j)
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enddo
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pchecks(i)=mod(nsum,2)
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enddo
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codeword(1:K)=message
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codeword(K+1:N)=pchecks
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return
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end subroutine encode_128_90
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@ -0,0 +1,114 @@
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subroutine genmsk_128_90(msg0,mygrid,ichk,bcontest,msgsent,i4tone,itype)
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! s8 + 48bits + s8 + 80 bits = 144 bits (72ms message duration)
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!
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! Encode an MSK144 message
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! Input:
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! - msg0 requested message to be transmitted
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! - ichk if ichk=1, return only msgsent
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! if ichk.ge.10000, set imsg=ichk-10000 for short msg
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! - msgsent message as it will be decoded
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! - i4tone array of audio tone values, 0 or 1
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! - itype message type
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! 1 = standard message "Call_1 Call_2 Grid/Rpt"
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! 2 = type 1 prefix
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! 3 = type 1 suffix
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! 4 = type 2 prefix
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! 5 = type 2 suffix
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! 6 = free text (up to 13 characters)
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! 7 = short message "<Call_1 Call2> Rpt"
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use iso_c_binding, only: c_loc,c_size_t
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use packjt77
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character*37 msg0
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character*37 message !Message to be generated
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character*37 msgsent !Message as it will be received
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character*77 c77
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character*6 mygrid
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integer*4 i4tone(144)
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integer*1 codeword(128)
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integer*1 msgbits(77)
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integer*1 bitseq(144) !Tone #s, data and sync (values 0-1)
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integer*1 s8(8)
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logical bcontest
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real*8 pp(12)
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real*8 xi(864),xq(864),pi,twopi
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data s8/0,1,1,1,0,0,1,0/
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equivalence (ihash,i1hash)
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logical first
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data first/.true./
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save
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if(first) then
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first=.false.
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nsym=128
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pi=4.0*atan(1.0)
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twopi=8.*atan(1.0)
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do i=1,12
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pp(i)=sin((i-1)*pi/12)
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enddo
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endif
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if(msg0(1:1).eq.'@') then !Generate a fixed tone
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read(msg0(2:5),*,end=1,err=1) nfreq !at specified frequency
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go to 2
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1 nfreq=1000
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2 i4tone(1)=nfreq
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else
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message=msg0
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do i=1,22
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if(ichar(message(i:i)).eq.0) then
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message(i:)=' '
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exit
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endif
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enddo
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do i=1,22 !Strip leading blanks
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if(message(1:1).ne.' ') exit
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message=message(i+1:)
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enddo
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if(message(1:1).eq.'<') then
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call genmsk40(message,msgsent,ichk,i4tone,itype)
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if(itype.lt.0) go to 999
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i4tone(41)=-40
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go to 999
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endif
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call pack77(message,i3,n3,c77)
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call unpack77(c77,msgsent) !Unpack to get msgsent
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if(ichk.eq.1) go to 999
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read(c77,"77i1") msgbits
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call encode_128_90(msgbits,codeword)
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!Create 144-bit channel vector:
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!8-bit sync word + 48 bits + 8-bit sync word + 80 bits
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bitseq=0
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bitseq(1:8)=s8
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bitseq(9:56)=codeword(1:48)
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bitseq(57:64)=s8
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bitseq(65:144)=codeword(49:128)
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bitseq=2*bitseq-1
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xq(1:6)=bitseq(1)*pp(7:12) !first bit is mapped to 1st half-symbol on q
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do i=1,71
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is=(i-1)*12+7
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xq(is:is+11)=bitseq(2*i+1)*pp
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enddo
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xq(864-5:864)=bitseq(1)*pp(1:6) !last half symbol
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do i=1,72
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is=(i-1)*12+1
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xi(is:is+11)=bitseq(2*i)*pp
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enddo
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! Map I and Q to tones.
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i4tone=0
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do i=1,72
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i4tone(2*i-1)=(bitseq(2*i)*bitseq(2*i-1)+1)/2;
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i4tone(2*i)=-(bitseq(2*i)*bitseq(mod(2*i,144)+1)-1)/2;
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enddo
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endif
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! Flip polarity
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i4tone=-i4tone+1
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999 return
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end subroutine genmsk_128_90
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@ -1,132 +1,134 @@
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program ldpcsim
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program ldpcsim128_90
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use packjt
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integer, parameter:: NRECENT=10, N=128, K=90, M=N-K
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character*12 recent_calls(NRECENT)
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character*22 msg,msgsent,msgreceived
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character*96 tmpchar
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character*8 arg
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integer*1 codeword(N), message77(77)
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integer*1 apmask(N),cw(N)
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integer*1 msgbits(77)
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integer*4 i4Msg6BitWords(13)
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integer nerrtot(0:N),nerrdec(0:N)
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real*8 rxdata(N), rxavgd(N)
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real llr(N)
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! Simulate the performance of the (128,90) code that is used in
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! the second incarnation of MSK144.
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do i=1,NRECENT
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recent_calls(i)=' '
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enddo
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nerrtot=0
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nerrdec=0
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use packjt77
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integer, parameter:: NRECENT=10, N=128, K=90, M=N-K
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character*12 recent_calls(NRECENT)
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character*37 msg,msgsent,msgreceived
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character*77 c77
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character*8 arg
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integer*1 codeword(N), message77(77)
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integer*1 apmask(N),cw(N)
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integer*1 msgbits(77)
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integer*4 i4Msg6BitWords(13)
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integer nerrtot(0:N),nerrdec(0:N)
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real*8 rxdata(N), rxavgd(N)
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real llr(N)
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nargs=iargc()
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if(nargs.ne.4) then
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print*,'Usage: ldpcsim niter navg #trials s '
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print*,'eg: ldpcsim 10 1 1000 0.75'
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return
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endif
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call getarg(1,arg)
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read(arg,*) max_iterations
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call getarg(2,arg)
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read(arg,*) navg
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call getarg(3,arg)
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read(arg,*) ntrials
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call getarg(4,arg)
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read(arg,*) s
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do i=1,NRECENT
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recent_calls(i)=' '
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enddo
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nerrtot=0
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nerrdec=0
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rate=real(K)/real(N)
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nargs=iargc()
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if(nargs.ne.4) then
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print*,'Usage: ldpcsim niter navg #trials s '
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print*,'eg: ldpcsim 10 1 1000 0.75'
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return
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endif
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call getarg(1,arg)
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read(arg,*) max_iterations
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call getarg(2,arg)
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read(arg,*) navg
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call getarg(3,arg)
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read(arg,*) ntrials
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call getarg(4,arg)
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read(arg,*) s
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write(*,*) "rate: ",rate
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write(*,*) "niter= ",max_iterations," navg= ",navg," s= ",s
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rate=real(77)/real(N)
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write(*,*) "rate: ",rate
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write(*,*) "niter= ",max_iterations," navg= ",navg," s= ",s
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msg="K1ABC RR73; W9XYZ <KH1/KH7Z> -12"
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i3=0
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n3=1
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call pack77(msg,i3,n3,c77)
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call unpack77(c77,msgsent)
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read(c77,'(77i1)') msgbits
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!msg="K9AN K1JT EN50"
|
||||
msg="G4WJS K1JT FN20"
|
||||
call packmsg(msg,i4Msg6BitWords,itype,.false.) !Pack into 12 6-bit bytes
|
||||
call unpackmsg(i4Msg6BitWords,msgsent,.false.,' ') !Unpack to get msgsent
|
||||
write(*,*) "message sent ",msgsent
|
||||
|
||||
tmpchar=' '
|
||||
write(tmpchar,'(12b6.6)') i4Msg6BitWords(1:12)
|
||||
tmpchar(73:77)="00000" !i5bit
|
||||
read(tmpchar,'(77i1)') msgbits(1:77)
|
||||
|
||||
write(*,*) 'msgbits'
|
||||
write(*,'(28i1,1x,28i1,1x,16i1,1x,5i1)') msgbits
|
||||
write(*,'(77i1)') msgbits
|
||||
|
||||
! msgbits is the 77-bit message, codeword is 128 bits
|
||||
call encode128_90(msgbits,codeword)
|
||||
call encode_128_90(msgbits,codeword)
|
||||
|
||||
call init_random_seed()
|
||||
! call init_random_seed()
|
||||
|
||||
write(*,*) "Eb/N0 SNR2500 ngood nundetected sigma psymerr"
|
||||
do idb = 14,-6,-1
|
||||
db=idb/2.0-1.0
|
||||
sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
|
||||
ngood=0
|
||||
nue=0
|
||||
nbadcrc=0
|
||||
nsumerr=0
|
||||
write(*,*) "Eb/N0 SNR2500 ngood nundetected sigma psymerr"
|
||||
do idb = 14,0,-1
|
||||
db=idb/2.0-1.0
|
||||
sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
|
||||
ngood=0
|
||||
nue=0
|
||||
nbadcrc=0
|
||||
nsumerr=0
|
||||
|
||||
do itrial=1, ntrials
|
||||
rxavgd=0d0
|
||||
do iav=1,navg
|
||||
call sgran()
|
||||
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()
|
||||
do i=1,N
|
||||
rxdata(i) = 2.0*codeword(i)-1.0 + sigma*gran()
|
||||
enddo
|
||||
rxavgd=rxavgd+rxdata
|
||||
enddo
|
||||
rxavgd=rxavgd+rxdata
|
||||
enddo
|
||||
rxdata=rxavgd
|
||||
nerr=0
|
||||
do i=1,N
|
||||
if( rxdata(i)*(2*codeword(i)-1.0) .lt. 0 ) nerr=nerr+1
|
||||
enddo
|
||||
nerrtot(nerr)=nerrtot(nerr)+1
|
||||
rxdata=rxavgd
|
||||
nerr=0
|
||||
do i=1,N
|
||||
if( rxdata(i)*(2*codeword(i)-1.0) .lt. 0 ) nerr=nerr+1
|
||||
enddo
|
||||
nerrtot(nerr)=nerrtot(nerr)+1
|
||||
|
||||
rxav=sum(rxdata)/N
|
||||
rx2av=sum(rxdata*rxdata)/N
|
||||
rxsig=sqrt(rx2av-rxav*rxav)
|
||||
rxdata=rxdata/rxsig
|
||||
rxav=sum(rxdata)/N
|
||||
rx2av=sum(rxdata*rxdata)/N
|
||||
rxsig=sqrt(rx2av-rxav*rxav)
|
||||
rxdata=rxdata/rxsig
|
||||
! The s parameter can be tuned to trade a few tenth's dB of threshold for an order of
|
||||
! magnitude in UER
|
||||
if( s .lt. 0 ) then
|
||||
ss=sigma
|
||||
else
|
||||
ss=s
|
||||
endif
|
||||
if( s .lt. 0 ) then
|
||||
ss=sigma
|
||||
else
|
||||
ss=s
|
||||
endif
|
||||
|
||||
llr=2.0*rxdata/(ss*ss)
|
||||
llr=2.0*rxdata/(ss*ss)
|
||||
|
||||
apmask=0
|
||||
apmask=0
|
||||
! max_iterations is max number of belief propagation iterations
|
||||
call bpdecode128_90(llr, apmask, max_iterations, message77, cw, nharderrors, niterations)
|
||||
call bpdecode128_90(llr, apmask, max_iterations, message77, cw, nharderrors, niterations)
|
||||
|
||||
! If the decoder finds a valid codeword, nharderrors will be .ge. 0.
|
||||
if( nharderrors .ge. 0 ) then
|
||||
call extractmessage77(message77,msgreceived)
|
||||
nhw=count(cw.ne.codeword)
|
||||
if(nhw.eq.0) then ! this is a good decode
|
||||
if( nharderrors .ge. 0 ) then
|
||||
write(c77,'(77i1)') message77
|
||||
call unpack77(c77,msgreceived)
|
||||
nhw=count(cw.ne.codeword)
|
||||
if(nhw.eq.0) then ! this is a good decode
|
||||
ngood=ngood+1
|
||||
nerrdec(nerr)=nerrdec(nerr)+1
|
||||
else ! this is an undetected error
|
||||
else ! this is an undetected error
|
||||
nue=nue+1
|
||||
endif
|
||||
endif
|
||||
nsumerr=nsumerr+nerr
|
||||
endif
|
||||
endif
|
||||
nsumerr=nsumerr+nerr
|
||||
enddo
|
||||
|
||||
snr2500=db+10*log10(rate*2000.0/2500.0) ! symbol rate is 2000 s^-1 and ref BW is 2500 Hz.
|
||||
pberr=real(nsumerr)/real(ntrials*N)
|
||||
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,7x,f5.2,3x,e10.3)") db,snr2500,ngood,nue,ss,pberr
|
||||
|
||||
enddo
|
||||
|
||||
snr2500=db-2.5
|
||||
pberr=real(nsumerr)/real(ntrials*N)
|
||||
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,7x,f5.2,3x,e10.3)") db,snr2500,ngood,nue,ss,pberr
|
||||
|
||||
enddo
|
||||
open(unit=23,file='nerrhisto.dat',status='unknown')
|
||||
do i=0,N
|
||||
write(23,'(i4,2x,i10,i10,f10.2)') i,nerrdec(i),nerrtot(i),real(nerrdec(i))/real(nerrtot(i)+1e-10)
|
||||
enddo
|
||||
close(23)
|
||||
|
||||
open(unit=23,file='nerrhisto.dat',status='unknown')
|
||||
do i=0,N
|
||||
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 ldpcsim
|
||||
end program ldpcsim128_90
|
||||
|
|
|
|||
|
|
@ -41,7 +41,7 @@ call getarg(4,arg)
|
|||
read(arg,*) s
|
||||
|
||||
! don't count hash bits as data bits
|
||||
K=80
|
||||
K=72
|
||||
N=128
|
||||
rate=real(K)/real(N)
|
||||
|
||||
|
|
@ -161,7 +161,7 @@ do idb = 14,-6,-1
|
|||
endif
|
||||
endif
|
||||
enddo
|
||||
snr2500=db-3.0
|
||||
snr2500=db-3.5
|
||||
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,1x,i8,8x,f5.2)") db,snr2500,ngood,nue,nbadhash,ss
|
||||
|
||||
enddo
|
||||
|
|
|
|||
Loading…
Reference in New Issue