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Add support for a rate 1/3 (204,68) code.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8585 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Steven Franke 2018-03-22 14:20:07 +00:00
parent 8b164ba17f
commit 2786c20ba2
5 changed files with 1298 additions and 0 deletions
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482
lib/fsk4hf/bpdecode204.f90 Normal file
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@ -0,0 +1,482 @@
subroutine bpdecode204(llr,apmask,maxiterations,decoded,cw,nharderror,iter)
!
! A log-domain belief propagation decoder for the (204,68) code.
!
integer, parameter:: N=204, K=68, M=N-K
integer*1 codeword(N),cw(N),apmask(N)
integer colorder(N)
integer*1 decoded(K)
integer Nm(6,M) ! 4, 5, or 6 bits per check
integer Mn(3,N) ! 3 checks per bit
integer synd(M)
real tov(3,N)
real toc(6,M)
real tanhtoc(6,M)
real zn(N)
real llr(N)
real Tmn
integer nrw(M)
data colorder/ &
0, 1, 2, 3, 4, 5, 47, 6, 7, 8, 9, 10, 11, 12, 58, 55, 13, &
14, 15, 46, 17, 18, 60, 19, 20, 21, 22, 23, 24, 25, 57, 26, 27, 49, &
28, 52, 65, 16, 50, 73, 59, 68, 63, 29, 30, 31, 32, 51, 62, 56, 66, &
45, 33, 34, 53, 67, 35, 36, 37, 61, 69, 54, 38, 71, 82, 39, 77, 80, &
83, 78, 84, 48, 41, 85, 40, 64, 75, 96, 74, 72, 76, 86, 87, 89, 90, &
79, 70, 92, 99, 93,101, 95,100, 97, 94, 42, 98,103,105,102, 43,104, &
88, 44,106, 81,107,110,108,111,112,109,113,114,117,118,116,121,115, &
119,122,120,125,129,124,127,126,128, 91,123,133,131,130,134,135,137, &
136,132,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152, &
153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169, &
170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186, &
187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203/
data Mn/ &
1, 38, 107, &
2, 7, 114, &
3, 48, 106, &
4, 79, 94, &
5, 97, 108, &
6, 50, 122, &
8, 78, 134, &
9, 55, 65, &
10, 62, 100, &
11, 16, 99, &
12, 113, 119, &
13, 31, 125, &
14, 15, 127, &
17, 87, 103, &
18, 81, 98, &
19, 43, 77, &
20, 102, 130, &
21, 36, 111, &
22, 23, 60, &
24, 39, 112, &
25, 37, 42, &
26, 41, 51, &
27, 67, 70, &
28, 64, 136, &
29, 61, 68, &
30, 91, 124, &
32, 80, 121, &
33, 40, 117, &
34, 35, 90, &
44, 88, 93, &
45, 128, 133, &
46, 56, 69, &
47, 49, 52, &
53, 76, 131, &
54, 104, 116, &
57, 84, 86, &
58, 120, 135, &
59, 75, 92, &
63, 71, 109, &
66, 74, 126, &
72, 85, 105, &
73, 82, 95, &
83, 89, 123, &
96, 115, 118, &
101, 110, 129, &
52, 99, 132, &
1, 3, 20, &
2, 77, 89, &
4, 72, 75, &
5, 34, 79, &
6, 24, 130, &
7, 48, 88, &
8, 36, 116, &
9, 71, 114, &
10, 87, 101, &
11, 22, 121, &
12, 50, 64, &
13, 39, 53, &
14, 41, 78, &
15, 68, 96, &
16, 83, 90, &
17, 23, 45, &
18, 47, 126, &
19, 70, 91, &
21, 57, 76, &
25, 110, 117, &
26, 82, 135, &
27, 46, 58, &
28, 37, 56, &
29, 66, 102, &
30, 62, 125, &
31, 85, 93, &
32, 104, 113, &
33, 81, 92, &
35, 100, 118, &
38, 95, 133, &
40, 86, 109, &
42, 61, 124, &
43, 59, 119, &
44, 49, 134, &
51, 97, 122, &
54, 105, 107, &
55, 128, 136, &
60, 67, 84, &
63, 112, 115, &
65, 74, 131, &
69, 80, 94, &
73, 98, 123, &
103, 130, 134, &
46, 106, 111, &
1, 84, 108, &
120, 129, 132, &
65, 75, 127, &
2, 80, 101, &
3, 118, 119, &
4, 52, 124, &
5, 13, 68, &
6, 27, 81, &
7, 51, 76, &
8, 77, 108, &
9, 31, 58, &
10, 18, 57, &
11, 63, 105, &
12, 14, 132, &
15, 56, 123, &
16, 21, 128, &
17, 37, 59, &
19, 85, 126, &
20, 71, 91, &
22, 26, 117, &
23, 79, 98, &
24, 32, 95, &
25, 90, 93, &
28, 49, 109, &
29, 116, 120, &
30, 54, 136, &
33, 53, 107, &
34, 64, 103, &
35, 39, 67, &
36, 71, 73, &
38, 47, 125, &
40, 66, 94, &
41, 70, 104, &
42, 55, 112, &
43, 44, 82, &
29, 45, 88, &
48, 86, 127, &
50, 72, 135, &
60, 74, 96, &
61, 121, 131, &
62, 78, 92, &
69, 100, 133, &
83, 122, 129, &
87, 97, 106, &
89, 102, 113, &
24, 99, 108, &
20, 72, 110, &
111, 115, 117, &
35, 52, 114, &
1, 44, 94, &
2, 23, 107, &
3, 81, 136, &
4, 8, 96, &
5, 37, 70, &
6, 43, 131, &
7, 103, 115, &
9, 94, 122, &
10, 68, 82, &
11, 56, 88, &
12, 46, 126, &
13, 16, 75, &
14, 79, 112, &
15, 47, 110, &
17, 36, 39, &
18, 63, 120, &
19, 22, 55, &
21, 49, 113, &
25, 54, 57, &
26, 89, 125, &
27, 101, 109, &
28, 31, 60, &
30, 74, 97, &
32, 92, 93, &
33, 83, 91, &
34, 58, 121, &
38, 65, 111, &
40, 99, 118, &
3, 41, 61, &
42, 50, 100, &
45, 78, 106, &
48, 95, 129, &
51, 85, 133, &
53, 59, 69, &
11, 62, 66, &
64, 73, 124, &
67, 123, 134, &
76, 104, 132, &
77, 100, 127, &
36, 80, 119, &
84, 102, 135, &
86, 105, 124, &
4, 87, 128, &
90, 106, 116, &
65, 98, 130, &
92, 108, 114, &
1, 52, 121, &
2, 84, 117, &
5, 83, 105, &
6, 15, 63, &
7, 28, 82, &
8, 32, 135, &
9, 104, 134, &
9, 10, 89, &
12, 62, 107, &
13, 40, 103, &
14, 31, 95, &
16, 27, 74, &
17, 90, 132, &
18, 34, 69, &
19, 103, 129, &
20, 76, 87, &
21, 22, 130, &
23, 25, 99, &
24, 101, 126/
data Nm/ &
1, 47, 91, 140, 186, 0, &
2, 48, 94, 141, 187, 0, &
3, 47, 95, 142, 168, 0, &
4, 49, 96, 143, 182, 0, &
5, 50, 97, 144, 188, 0, &
6, 51, 98, 145, 189, 0, &
2, 52, 99, 146, 190, 0, &
7, 53, 100, 143, 191, 0, &
8, 54, 101, 147, 192, 193, &
9, 55, 102, 148, 193, 0, &
10, 56, 103, 149, 174, 0, &
11, 57, 104, 150, 194, 0, &
12, 58, 97, 151, 195, 0, &
13, 59, 104, 152, 196, 0, &
13, 60, 105, 153, 189, 0, &
10, 61, 106, 151, 197, 0, &
14, 62, 107, 154, 198, 0, &
15, 63, 102, 155, 199, 0, &
16, 64, 108, 156, 200, 0, &
17, 47, 109, 137, 201, 0, &
18, 65, 106, 157, 202, 0, &
19, 56, 110, 156, 202, 0, &
19, 62, 111, 141, 203, 0, &
20, 51, 112, 136, 204, 0, &
21, 66, 113, 158, 203, 0, &
22, 67, 110, 159, 0, 0, &
23, 68, 98, 160, 197, 0, &
24, 69, 114, 161, 190, 0, &
25, 70, 115, 126, 0, 0, &
26, 71, 116, 162, 0, 0, &
12, 72, 101, 161, 196, 0, &
27, 73, 112, 163, 191, 0, &
28, 74, 117, 164, 0, 0, &
29, 50, 118, 165, 199, 0, &
29, 75, 119, 139, 0, 0, &
18, 53, 120, 154, 179, 0, &
21, 69, 107, 144, 0, 0, &
1, 76, 121, 166, 0, 0, &
20, 58, 119, 154, 0, 0, &
28, 77, 122, 167, 195, 0, &
22, 59, 123, 168, 0, 0, &
21, 78, 124, 169, 0, 0, &
16, 79, 125, 145, 0, 0, &
30, 80, 125, 140, 0, 0, &
31, 62, 126, 170, 0, 0, &
32, 68, 90, 150, 0, 0, &
33, 63, 121, 153, 0, 0, &
3, 52, 127, 171, 0, 0, &
33, 80, 114, 157, 0, 0, &
6, 57, 128, 169, 0, 0, &
22, 81, 99, 172, 0, 0, &
33, 46, 96, 139, 186, 0, &
34, 58, 117, 173, 0, 0, &
35, 82, 116, 158, 0, 0, &
8, 83, 124, 156, 0, 0, &
32, 69, 105, 149, 0, 0, &
36, 65, 102, 158, 0, 0, &
37, 68, 101, 165, 0, 0, &
38, 79, 107, 173, 0, 0, &
19, 84, 129, 161, 0, 0, &
25, 78, 130, 168, 0, 0, &
9, 71, 131, 174, 194, 0, &
39, 85, 103, 155, 189, 0, &
24, 57, 118, 175, 0, 0, &
8, 86, 93, 166, 184, 0, &
40, 70, 122, 174, 0, 0, &
23, 84, 119, 176, 0, 0, &
25, 60, 97, 148, 0, 0, &
32, 87, 132, 173, 199, 0, &
23, 64, 123, 144, 0, 0, &
39, 54, 109, 120, 0, 0, &
41, 49, 128, 137, 0, 0, &
42, 88, 120, 175, 0, 0, &
40, 86, 129, 162, 197, 0, &
38, 49, 93, 151, 0, 0, &
34, 65, 99, 177, 201, 0, &
16, 48, 100, 178, 0, 0, &
7, 59, 131, 170, 0, 0, &
4, 50, 111, 152, 0, 0, &
27, 87, 94, 179, 0, 0, &
15, 74, 98, 142, 0, 0, &
42, 67, 125, 148, 190, 0, &
43, 61, 133, 164, 188, 0, &
36, 84, 91, 180, 187, 0, &
41, 72, 108, 172, 0, 0, &
36, 77, 127, 181, 0, 0, &
14, 55, 134, 182, 201, 0, &
30, 52, 126, 149, 0, 0, &
43, 48, 135, 159, 193, 0, &
29, 61, 113, 183, 198, 0, &
26, 64, 109, 164, 0, 0, &
38, 74, 131, 163, 185, 0, &
30, 72, 113, 163, 0, 0, &
4, 87, 122, 140, 147, 0, &
42, 76, 112, 171, 196, 0, &
44, 60, 129, 143, 0, 0, &
5, 81, 134, 162, 0, 0, &
15, 88, 111, 184, 0, 0, &
10, 46, 136, 167, 203, 0, &
9, 75, 132, 169, 178, 0, &
45, 55, 94, 160, 204, 0, &
17, 70, 135, 180, 0, 0, &
14, 89, 118, 146, 195, 200, &
35, 73, 123, 177, 192, 0, &
41, 82, 103, 181, 188, 0, &
3, 90, 134, 170, 183, 0, &
1, 82, 117, 141, 194, 0, &
5, 91, 100, 136, 185, 0, &
39, 77, 114, 160, 0, 0, &
45, 66, 137, 153, 0, 0, &
18, 90, 138, 166, 0, 0, &
20, 85, 124, 152, 0, 0, &
11, 73, 135, 157, 0, 0, &
2, 54, 139, 185, 0, 0, &
44, 85, 138, 146, 0, 0, &
35, 53, 115, 183, 0, 0, &
28, 66, 110, 138, 187, 0, &
44, 75, 95, 167, 0, 0, &
11, 79, 95, 179, 0, 0, &
37, 92, 115, 155, 0, 0, &
27, 56, 130, 165, 186, 0, &
6, 81, 133, 147, 0, 0, &
43, 88, 105, 176, 0, 0, &
26, 78, 96, 175, 181, 0, &
12, 71, 121, 159, 0, 0, &
40, 63, 108, 150, 204, 0, &
13, 93, 127, 178, 0, 0, &
31, 83, 106, 182, 0, 0, &
45, 92, 133, 171, 200, 0, &
17, 51, 89, 184, 202, 0, &
34, 86, 130, 145, 0, 0, &
46, 92, 104, 177, 198, 0, &
31, 76, 132, 172, 0, 0, &
7, 80, 89, 176, 192, 0, &
37, 67, 128, 180, 191, 0, &
24, 83, 116, 142, 0, 0/
data nrw/ &
5,5,5,5,5,5,5,5,6,5,5,5,5,5,5,5,5, &
5,5,5,5,5,5,5,5,4,5,5,4,4,5,5,4,5, &
4,5,4,4,4,5,4,4,4,4,4,4,4,4,4,4,4, &
5,4,4,4,4,4,4,4,4,4,5,5,4,5,4,4,4, &
5,4,4,4,4,5,4,5,4,4,4,4,4,5,5,5,4, &
4,5,4,5,5,4,5,4,5,5,4,4,4,5,5,5,4, &
6,5,5,5,5,5,4,4,4,4,4,4,4,4,5,4,4, &
4,5,4,4,5,4,5,4,4,5,5,4,5,4,5,5,4/
ncw=3
decoded=0
toc=0
tov=0
tanhtoc=0
! initialize messages to checks
do j=1,M
do i=1,nrw(j)
toc(i,j)=llr((Nm(i,j)))
enddo
enddo
ncnt=0
do iter=0,maxiterations
! Update bit log likelihood ratios (tov=0 in iteration 0).
do i=1,N
if( apmask(i) .ne. 1 ) then
zn(i)=llr(i)+sum(tov(1:ncw,i))
else
zn(i)=llr(i)
endif
enddo
! Check to see if we have a codeword (check before we do any iteration).
cw=0
where( zn .gt. 0. ) cw=1
ncheck=0
do i=1,M
synd(i)=sum(cw(Nm(1:nrw(i),i)))
if( mod(synd(i),2) .ne. 0 ) ncheck=ncheck+1
! if( mod(synd(i),2) .ne. 0 ) write(*,*) 'check ',i,' unsatisfied'
enddo
! write(*,*) 'number of unsatisfied parity checks ',ncheck
if( ncheck .eq. 0 ) then ! we have a codeword - reorder the columns and return it
codeword=cw(colorder+1)
decoded=codeword(M+1:N)
nerr=0
do i=1,N
if( (2*cw(i)-1)*llr(i) .lt. 0.0 ) nerr=nerr+1
enddo
nharderror=nerr
return
endif
if( iter.gt.0 ) then ! this code block implements an early stopping criterion
! if( iter.gt.10000 ) then ! this code block implements an early stopping criterion
nd=ncheck-nclast
if( nd .lt. 0 ) then ! # of unsatisfied parity checks decreased
ncnt=0 ! reset counter
else
ncnt=ncnt+1
endif
! write(*,*) iter,ncheck,nd,ncnt
if( ncnt .ge. 5 .and. iter .ge. 10 .and. ncheck .gt. 15) then
nharderror=-1
return
endif
endif
nclast=ncheck
! Send messages from bits to check nodes
do j=1,M
do i=1,nrw(j)
ibj=Nm(i,j)
toc(i,j)=zn(ibj)
do kk=1,ncw ! subtract off what the bit had received from the check
if( Mn(kk,ibj) .eq. j ) then
toc(i,j)=toc(i,j)-tov(kk,ibj)
endif
enddo
enddo
enddo
! send messages from check nodes to variable nodes
do i=1,M
tanhtoc(1:6,i)=tanh(-toc(1:6,i)/2)
enddo
do j=1,N
do i=1,ncw
ichk=Mn(i,j) ! Mn(:,j) are the checks that include bit j
Tmn=product(tanhtoc(1:nrw(ichk),ichk),mask=Nm(1:nrw(ichk),ichk).ne.j)
call platanh(-Tmn,y)
! y=atanh(-Tmn)
tov(i,j)=2*y
enddo
enddo
enddo
nharderror=-1
return
end subroutine bpdecode204

48
lib/fsk4hf/encode204.f90 Normal file
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@ -0,0 +1,48 @@
subroutine encode204(message,codeword)
! Encode an 68-bit message and return a 204-bit codeword.
! The generator matrix has dimensions (136,68).
! The code is a (204,68) regular ldpc code with column weight 3.
! The code was generated using the PEG algorithm.
! After creating the codeword, the columns are re-ordered according to
! "colorder" to make the codeword compatible with the parity-check matrix
!
include "ldpc_204_68_params.f90"
integer*1 codeword(N)
integer*1 gen(M,K)
integer*1 itmp(N)
integer*1 message(K)
integer*1 pchecks(M)
logical first
data first/.true./
save first,gen
if( first ) then ! fill the generator matrix
gen=0
do i=1,M
do j=1,17
read(g(i)(j:j),"(Z1)") istr
do jj=1, 4
icol=(j-1)*4+jj
if( btest(istr,4-jj) ) gen(i,icol)=1
enddo
enddo
enddo
first=.false.
endif
do i=1,M
nsum=0
do j=1,K
nsum=nsum+message(j)*gen(i,j)
enddo
pchecks(i)=mod(nsum,2)
enddo
itmp(1:M)=pchecks
itmp(M+1:N)=message(1:K)
codeword(colorder+1)=itmp(1:N)
return
end subroutine encode204

154
lib/fsk4hf/ldpc_204_68_params.f90 Normal file
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@ -0,0 +1,154 @@
integer, parameter:: N=204, K=68, M=N-K
character*17 g(136)
integer colorder(N)
data g/ & !parity generator matrix for (204,68) code
"2de7435fd27c0031d", &
"f331b40671e20ea80", &
"48bd3f8cb9a24392f", &
"d4ed71c935162aa2a", &
"c437a3284ec58bce7", &
"35a806dd5be35627c", &
"396e797c33a4739a6", &
"768f331a59c15487b", &
"c214eac24ae5e1732", &
"0b5c53ff3a6da1192", &
"99624981d2703fb97", &
"e9f5447ef7f1ff6af", &
"bd8c730f0cfdf0727", &
"26f61e63e1e098f7f", &
"ef826566137b6526f", &
"af0e4fa251e9b4926", &
"75974a8b2a24292c5", &
"71caf0f2cd10f6d4f", &
"b1103f1f26e6898b7", &
"67ceb7d6f490da64f", &
"ee0e8fbefec23008a", &
"11cc2227e8bd676ca", &
"6e71626ba1e278046", &
"005d28da267e50e13", &
"a9ae4a130aaba8219", &
"d8ab72e0158d0da70", &
"56009d42b37bd66ff", &
"c39a75eca99b0e996", &
"6886de0bf7c0bf4bb", &
"1046cd8f64162f7b5", &
"da0f15843ac21e3a5", &
"e9bf9cd19f3db3913", &
"2fb9cb42d650f47a7", &
"a2b6c5a378fa75a65", &
"41a88f3cd60b79d6c", &
"fcf175794cc3ac96a", &
"8677a3447d40a9f71", &
"97a1f08c250b4bf12", &
"0168f090a1df6e8ea", &
"418a06bf372cc67d9", &
"0f17b880c1ff51239", &
"b2afd6d585deb961b", &
"60298ac5b58dbeee0", &
"8350c03c40119feff", &
"b29c964a8accf6af4", &
"9b46f036a5c178b5d", &
"917398bff051c300a", &
"5e52c03b2f8c5128c", &
"beae6c33c87ba38ab", &
"20843f7b056a02ebf", &
"66690d65acd9de598", &
"8f025841af5b54331", &
"b43cd869d3be2c3db", &
"c9c342fe63c18df50", &
"d331b40671e28ea80", &
"62406a0f4947e6ce9", &
"d67b1495883b22e1b", &
"734534c372408895b", &
"d88750e33d9677dcd", &
"6f96964da55138687", &
"80bee98bb75d50ef2", &
"c428ef3e3f06f4c56", &
"b1a1499b125883a35", &
"ac892d4b37fa9e395", &
"458dbda0f95ab11a5", &
"6f93c9e95b1094eed", &
"2e370d713914f848e", &
"758806dd5be35627c", &
"8c52e01caec798b49", &
"c286cc25bae3669cf", &
"87c56fb895c100884", &
"e89cb1376a18fd911", &
"156ffe5f30dc354e0", &
"f20d0b121d6a6b3ee", &
"7db08891b491a95d2", &
"191fac548d5077bdf", &
"023a37d7ea5660bbc", &
"6781668b363fee682", &
"bbfaf262cab7370da", &
"feea557965b7e474f", &
"c094eb223e1d305b8", &
"2be051abdd5beea35", &
"0790449880fda9d00", &
"f9029a39ec869e7b4", &
"5a29f48926ec9a552", &
"e0463306dc1470f87", &
"9251058334d790f86", &
"3019e1d4578e8a4dc", &
"887e46631502fa111", &
"c25fcd7a42465d326", &
"cf64bcc1056b555c4", &
"3e71c0fe5f0ad733b", &
"11055ec43b076e5b2", &
"3440f64dfa3c30a96", &
"2b73885b4d3299f60", &
"2e71627ba1e268046", &
"ad23743d5e6e5b80c", &
"c9757b05f29bfdc10", &
"f7112bea739247b51", &
"3664062387998b2b1", &
"90897a3b8785aefba", &
"29e126e3201fc1d46", &
"96c9001c84d5257fc", &
"067723447d40a9f71", &
"1a019cc68f7511402", &
"4bd48eb2330032763", &
"d139a5da936b37647", &
"765ab46a4dec5f04f", &
"706f475ad19b91955", &
"1755c988fa8a55e5c", &
"2fd9ed5777eb01d6a", &
"bec27d85b954d3fe8", &
"7135a3b92c45b3f8d", &
"353237872f002163a", &
"e31e4a97aef10c729", &
"da527d5e1cbc4edb6", &
"6e33cdede17c3207e", &
"ef2d2062e84dc401f", &
"8217c84c50c1bf833", &
"12ffbac7b2219c9e0", &
"3729178706f66881f", &
"2fdd748c382a608a1", &
"dd0a00076f9dcec73", &
"46b1d37bced447035", &
"7316f33a9c05ef178", &
"152c39a6de8954cc3", &
"16efffb7b62e12ba3", &
"9d9ec2bb467affd83", &
"467723445d40a9f61", &
"87994762b3bf50697", &
"b1bfa5b51526dde9b", &
"b0a6a19d709a96148", &
"990d567c0aba31a14", &
"171f190792461b1e0", &
"166011c27d2b6b8a4", &
"170c15831244ae73e"/
data colorder/ &
0, 1, 2, 3, 4, 5, 47, 6, 7, 8, 9, 10, 11, 12, 58, 55, 13, &
14, 15, 46, 17, 18, 60, 19, 20, 21, 22, 23, 24, 25, 57, 26, 27, 49, &
28, 52, 65, 16, 50, 73, 59, 68, 63, 29, 30, 31, 32, 51, 62, 56, 66, &
45, 33, 34, 53, 67, 35, 36, 37, 61, 69, 54, 38, 71, 82, 39, 77, 80, &
83, 78, 84, 48, 41, 85, 40, 64, 75, 96, 74, 72, 76, 86, 87, 89, 90, &
79, 70, 92, 99, 93,101, 95,100, 97, 94, 42, 98,103,105,102, 43,104, &
88, 44,106, 81,107,110,108,111,112,109,113,114,117,118,116,121,115, &
119,122,120,125,129,124,127,126,128, 91,123,133,131,130,134,135,137, &
136,132,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152, &
153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169, &
170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186, &
187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203/

249
lib/fsk4hf/ldpcsim204.f90 Normal file
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@ -0,0 +1,249 @@
program ldpcsim204
! End-to-end test of the (300,60)/crc10 encoder and decoders.
use crc
use packjt
parameter(NRECENT=10)
character*12 recent_calls(NRECENT)
character*8 arg
integer*1, allocatable :: codeword(:), decoded(:), message(:)
integer*1, target:: i1Msg8BitBytes(9)
integer*1, target:: i1Dec8BitBytes(9)
integer*1 msgbits(68)
integer*1 apmask(204)
integer*1 cw(204)
integer*2 checksum
integer colorder(204)
integer nerrtot(204),nerrdec(204),nmpcbad(68)
logical checksumok,fsk,bpsk
real*8, allocatable :: rxdata(:)
real, allocatable :: llr(:)
real dllr(204),llrd(204)
data colorder/ &
0, 1, 2, 3, 4, 5, 47, 6, 7, 8, 9, 10, 11, 12, 58, 55, 13, &
14, 15, 46, 17, 18, 60, 19, 20, 21, 22, 23, 24, 25, 57, 26, 27, 49, &
28, 52, 65, 16, 50, 73, 59, 68, 63, 29, 30, 31, 32, 51, 62, 56, 66, &
45, 33, 34, 53, 67, 35, 36, 37, 61, 69, 54, 38, 71, 82, 39, 77, 80, &
83, 78, 84, 48, 41, 85, 40, 64, 75, 96, 74, 72, 76, 86, 87, 89, 90, &
79, 70, 92, 99, 93,101, 95,100, 97, 94, 42, 98,103,105,102, 43,104, &
88, 44,106, 81,107,110,108,111,112,109,113,114,117,118,116,121,115, &
119,122,120,125,129,124,127,126,128, 91,123,133,131,130,134,135,137, &
136,132,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152, &
153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169, &
170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186, &
187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203/
do i=1,NRECENT
recent_calls(i)=' '
enddo
nerrtot=0
nerrdec=0
nmpcbad=0 ! Used to collect the number of errors in the message+crc part of the codeword
nargs=iargc()
if(nargs.ne.4) then
print*,'Usage: ldpcsim niter ndeep #trials s '
print*,'eg: ldpcsim 100 4 1000 0.84'
print*,'If s is negative, then value is ignored and sigma is calculated from SNR.'
return
endif
call getarg(1,arg)
read(arg,*) max_iterations
call getarg(2,arg)
read(arg,*) ndeep
call getarg(3,arg)
read(arg,*) ntrials
call getarg(4,arg)
read(arg,*) s
fsk=.false.
bpsk=.true.
N=204
K=68
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) )
! The message should be packed into the first 7 bytes
i1Msg8BitBytes(1:6)=85
i1Msg8BitBytes(7)=64
! The CRC will be put into the last 2 bytes
i1Msg8BitBytes(8:9)=0
checksum = crc10 (c_loc (i1Msg8BitBytes), 9)
! For reference, the next 3 lines show how to check the CRC
i1Msg8BitBytes(8)=checksum/256
i1Msg8BitBytes(9)=iand (checksum,255)
checksumok = crc10_check(c_loc (i1Msg8BitBytes), 9)
if( checksumok ) write(*,*) 'Good checksum'
write(*,*) i1Msg8BitBytes(1:9)
mbit=0
do i=1, 7
i1=i1Msg8BitBytes(i)
do ibit=1,8
mbit=mbit+1
msgbits(mbit)=iand(1,ishft(i1,ibit-8))
enddo
enddo
i1=i1Msg8BitBytes(8) ! First 2 bits of crc10 are LSB of this byte
do ibit=1,2
msgbits(50+ibit)=iand(1,ishft(i1,ibit-2))
enddo
i1=i1Msg8BitBytes(9) ! Now shift in last 8 bits of the CRC
do ibit=1,8
msgbits(52+ibit)=iand(1,ishft(i1,ibit-8))
enddo
write(*,*) 'message'
write(*,'(9(8i1,1x))') msgbits
call encode204(msgbits,codeword)
call init_random_seed()
call sgran()
write(*,*) 'codeword'
write(*,'(204i1)') codeword
write(*,*) "Es/N0 SNR2500 ngood nundetected nbadcrc sigma"
do idb = 20,-18,-1
!do idb = -16, -16, -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
nbadcrc=0
nberr=0
do itrial=1, ntrials
! Create a realization of a noisy received word
do i=1,N
if( bpsk ) then
rxdata(i) = 2.0*codeword(i)-1.0 + sigma*gran()
elseif( fsk ) then
if( codeword(i) .eq. 1 ) then
r1=(1.0 + sigma*gran())**2 + (sigma*gran())**2
r2=(sigma*gran())**2 + (sigma*gran())**2
elseif( codeword(i) .eq. 0 ) then
r2=(1.0 + sigma*gran())**2 + (sigma*gran())**2
r1=(sigma*gran())**2 + (sigma*gran())**2
endif
rxdata(i)=0.35*(sqrt(r1)-sqrt(r2))
! rxdata(i)=0.35*(exp(r1)-exp(r2))
! rxdata(i)=0.12*(log(r1)-log(r2))
endif
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
nberr=nberr+nerr
! 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
! 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 .lt. 0 ) then
ss=sigma
else
ss=s
endif
llr=2.0*rxdata/(ss*ss)
apmask=0
! max_iterations is max number of belief propagation iterations
call bpdecode204(llr,apmask,max_iterations,decoded,cw,nharderror,niterations)
if( (nharderror .lt. 0) .and. (ndeep .ge. 0) ) then
call osd204(llr, apmask, ndeep, decoded, cw, nhardmin, dmin)
niterations=nhardmin
endif
n2err=0
do i=1,N
if( cw(i)*(2*codeword(i)-1.0) .lt. 0 ) n2err=n2err+1
enddo
!write(*,*) nerr,niterations,n2err
damp=0.75
ndither=0
if( niterations .lt. 0 ) then
do i=1, ndither
do in=1,N
dllr(in)=damp*gran()
enddo
llrd=llr+dllr
call bpdecode300(llrd, apmask, max_iterations, decoded, cw, nharderror, niterations)
if( niterations .ge. 0 ) exit
enddo
endif
! If the decoder finds a valid codeword, niterations will be .ge. 0.
if( niterations .ge. 0 ) then
! Check the CRC
do ibyte=1,6
itmp=0
do ibit=1,8
itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*8+ibit))
enddo
i1Dec8BitBytes(ibyte)=itmp
enddo
i1Dec8BitBytes(7)=decoded(49)*128+decoded(50)*64
! Need to pack the received crc into bytes 8 and 9 for crc10_check
i1Dec8BitBytes(8)=decoded(51)*2+decoded(52)
i1Dec8BitBytes(9)=decoded(53)*128+decoded(54)*64+decoded(55)*32+decoded(56)*16
i1Dec8BitBytes(9)=i1Dec8BitBytes(9)+decoded(57)*8+decoded(58)*4+decoded(59)*2+decoded(60)*1
ncrcflag=0
if( crc10_check( c_loc( i1Dec8BitBytes ), 9 ) ) ncrcflag=1
if( ncrcflag .ne. 1 ) then
nbadcrc=nbadcrc+1
endif
nueflag=0
nerrmpc=0
do i=1,K ! find number of errors in message+crc part of codeword
if( msgbits(i) .ne. decoded(i) ) then
nueflag=1
nerrmpc=nerrmpc+1
endif
enddo
if(nerrmpc.ge.1) nmpcbad(nerrmpc)=nmpcbad(nerrmpc)+1 ! This histogram should inform our selection of CRC poly
if( ncrcflag .eq. 1 .and. nueflag .eq. 0 ) then
ngood=ngood+1
if(nerr.ge.1) nerrdec(nerr)=nerrdec(nerr)+1
else if( ncrcflag .eq. 1 .and. nueflag .eq. 1 ) then
nue=nue+1;
endif
endif
enddo
snr2500=db+10*log10(1.389/2500.0)
pberr=real(nberr)/(real(ntrials*N))
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,1x,i8,8x,f5.2,8x,e10.3)") db,snr2500,ngood,nue,nbadcrc,ss,pberr
enddo
open(unit=23,file='nerrhisto.dat',status='unknown')
do i=1,120
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=25,file='nmpcbad.dat',status='unknown')
do i=1,68
write(25,'(i4,2x,i10)') i,nmpcbad(i)
enddo
close(25)
end program ldpcsim204

365
lib/fsk4hf/osd204.f90 Normal file
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@ -0,0 +1,365 @@
subroutine osd204(llr,apmask,ndeep,decoded,cw,nhardmin,dmin)
!
! An ordered-statistics decoder for the (204,68) code.
!
include "ldpc_204_68_params.f90"
integer*1 apmask(N),apmaskr(N)
integer*1 gen(K,N)
integer*1 genmrb(K,N),g2(N,K)
integer*1 temp(K),m0(K),me(K),mi(K),misub(K),e2sub(N-K),e2(N-K),ui(N-K)
integer*1 r2pat(N-K)
integer indices(N),nxor(N)
integer*1 cw(N),ce(N),c0(N),hdec(N)
integer*1 decoded(K)
integer indx(N)
real llr(N),rx(N),absrx(N)
logical first,reset
data first/.true./
save first,gen
if( first ) then ! fill the generator matrix
gen=0
do i=1,M
do j=1,17
read(g(i)(j:j),"(Z1)") istr
do jj=1, 4
irow=(j-1)*4+jj
if( btest(istr,4-jj) ) gen(irow,i)=1
enddo
enddo
enddo
do irow=1,K
gen(irow,M+irow)=1
enddo
first=.false.
endif
! Re-order received vector to place systematic msg bits at the end.
rx=llr(colorder+1)
apmaskr=apmask(colorder+1)
! Hard decisions on the received word.
hdec=0
where(rx .ge. 0) hdec=1
! Use magnitude of received symbols as a measure of reliability.
absrx=abs(rx)
call indexx(absrx,N,indx)
! Re-order the columns of the generator matrix in order of decreasing reliability.
do i=1,N
genmrb(1:K,i)=gen(1:K,indx(N+1-i))
indices(i)=indx(N+1-i)
enddo
! Do gaussian elimination to create a generator matrix with the most reliable
! received bits in positions 1:K in order of decreasing reliability (more or less).
do id=1,K ! diagonal element indices
do icol=id,K+20 ! The 20 is ad hoc - beware
iflag=0
if( genmrb(id,icol) .eq. 1 ) then
iflag=1
if( icol .ne. id ) then ! reorder column
temp(1:K)=genmrb(1:K,id)
genmrb(1:K,id)=genmrb(1:K,icol)
genmrb(1:K,icol)=temp(1:K)
itmp=indices(id)
indices(id)=indices(icol)
indices(icol)=itmp
endif
do ii=1,K
if( ii .ne. id .and. genmrb(ii,id) .eq. 1 ) then
genmrb(ii,1:N)=ieor(genmrb(ii,1:N),genmrb(id,1:N))
endif
enddo
exit
endif
enddo
enddo
g2=transpose(genmrb)
! The hard decisions for the K MRB bits define the order 0 message, m0.
! Encode m0 using the modified generator matrix to find the "order 0" codeword.
! Flip various combinations of bits in m0 and re-encode to generate a list of
! codewords. Return the member of the list that has the smallest Euclidean
! distance to the received word.
hdec=hdec(indices) ! hard decisions from received symbols
m0=hdec(1:K) ! zero'th order message
absrx=absrx(indices)
rx=rx(indices)
apmaskr=apmaskr(indices)
call mrbencode(m0,c0,g2,N,K)
nxor=ieor(c0,hdec)
nhardmin=sum(nxor)
dmin=sum(nxor*absrx)
cw=c0
ntotal=0
nrejected=0
if(ndeep.eq.0) goto 998 ! norder=0
if(ndeep.gt.5) ndeep=5
if( ndeep.eq. 1) then
nord=1
npre1=0
npre2=0
nt=40
ntheta=12
elseif(ndeep.eq.2) then
nord=1
npre1=1
npre2=0
nt=40
ntheta=12
elseif(ndeep.eq.3) then
nord=1
npre1=1
npre2=1
nt=40
ntheta=12
ntau=14
elseif(ndeep.eq.4) then
nord=2
npre1=1
npre2=0
nt=40
ntheta=12
ntau=19
elseif(ndeep.eq.5) then
nord=2
npre1=1
npre2=1
nt=40
ntheta=12
ntau=19
endif
do iorder=1,nord
misub(1:K-iorder)=0
misub(K-iorder+1:K)=1
iflag=K-iorder+1
do while(iflag .ge.0)
if(iorder.eq.nord .and. npre1.eq.0) then
iend=iflag
else
iend=1
endif
do n1=iflag,iend,-1
mi=misub
mi(n1)=1
if(any(iand(apmaskr(1:K),mi).eq.1)) cycle
ntotal=ntotal+1
me=ieor(m0,mi)
if(n1.eq.iflag) then
call mrbencode(me,ce,g2,N,K)
e2sub=ieor(ce(K+1:N),hdec(K+1:N))
e2=e2sub
nd1Kpt=sum(e2sub(1:nt))+1
d1=sum(ieor(me(1:K),hdec(1:K))*absrx(1:K))
else
e2=ieor(e2sub,g2(K+1:N,n1))
nd1Kpt=sum(e2(1:nt))+2
endif
if(nd1Kpt .le. ntheta) then
call mrbencode(me,ce,g2,N,K)
nxor=ieor(ce,hdec)
if(n1.eq.iflag) then
dd=d1+sum(e2sub*absrx(K+1:N))
else
dd=d1+ieor(ce(n1),hdec(n1))*absrx(n1)+sum(e2*absrx(K+1:N))
endif
if( dd .lt. dmin ) then
dmin=dd
cw=ce
nhardmin=sum(nxor)
nd1Kptbest=nd1Kpt
endif
else
nrejected=nrejected+1
endif
enddo
! Get the next test error pattern, iflag will go negative
! when the last pattern with weight iorder has been generated.
call nextpat(misub,k,iorder,iflag)
enddo
enddo
if(npre2.eq.1) then
reset=.true.
ntotal=0
do i1=K,1,-1
do i2=i1-1,1,-1
ntotal=ntotal+1
mi(1:ntau)=ieor(g2(K+1:K+ntau,i1),g2(K+1:K+ntau,i2))
call boxit(reset,mi(1:ntau),ntau,ntotal,i1,i2)
enddo
enddo
ncount2=0
ntotal2=0
reset=.true.
! Now run through again and do the second pre-processing rule
misub(1:K-nord)=0
misub(K-nord+1:K)=1
iflag=K-nord+1
do while(iflag .ge.0)
me=ieor(m0,misub)
call mrbencode(me,ce,g2,N,K)
e2sub=ieor(ce(K+1:N),hdec(K+1:N))
do i2=0,ntau
ntotal2=ntotal2+1
ui=0
if(i2.gt.0) ui(i2)=1
r2pat=ieor(e2sub,ui)
778 continue
call fetchit(reset,r2pat(1:ntau),ntau,in1,in2)
if(in1.gt.0.and.in2.gt.0) then
ncount2=ncount2+1
mi=misub
mi(in1)=1
mi(in2)=1
if(sum(mi).lt.nord+npre1+npre2.or.any(iand(apmaskr(1:K),mi).eq.1)) cycle
me=ieor(m0,mi)
call mrbencode(me,ce,g2,N,K)
nxor=ieor(ce,hdec)
dd=sum(nxor*absrx)
if( dd .lt. dmin ) then
dmin=dd
cw=ce
nhardmin=sum(nxor)
endif
goto 778
endif
enddo
call nextpat(misub,K,nord,iflag)
enddo
endif
998 continue
! Re-order the codeword to place message bits at the end.
cw(indices)=cw
hdec(indices)=hdec
decoded=cw(M+1:N)
cw(colorder+1)=cw ! put the codeword back into received-word order
return
end subroutine osd204
subroutine mrbencode(me,codeword,g2,N,K)
integer*1 me(K),codeword(N),g2(N,K)
! fast encoding for low-weight test patterns
codeword=0
do i=1,K
if( me(i) .eq. 1 ) then
codeword=ieor(codeword,g2(1:N,i))
endif
enddo
return
end subroutine mrbencode
subroutine nextpat(mi,k,iorder,iflag)
integer*1 mi(k),ms(k)
! generate the next test error pattern
ind=-1
do i=1,k-1
if( mi(i).eq.0 .and. mi(i+1).eq.1) ind=i
enddo
if( ind .lt. 0 ) then ! no more patterns of this order
iflag=ind
return
endif
ms=0
ms(1:ind-1)=mi(1:ind-1)
ms(ind)=1
ms(ind+1)=0
if( ind+1 .lt. k ) then
nz=iorder-sum(ms)
ms(k-nz+1:k)=1
endif
mi=ms
do i=1,k ! iflag will point to the lowest-index 1 in mi
if(mi(i).eq.1) then
iflag=i
exit
endif
enddo
return
end subroutine nextpat
subroutine boxit(reset,e2,ntau,npindex,i1,i2)
integer*1 e2(1:ntau)
integer indexes(4000,2),fp(0:525000),np(4000)
logical reset
common/boxes/indexes,fp,np
if(reset) then
patterns=-1
fp=-1
np=-1
sc=-1
indexes=-1
reset=.false.
endif
indexes(npindex,1)=i1
indexes(npindex,2)=i2
ipat=0
do i=1,ntau
if(e2(i).eq.1) then
ipat=ipat+ishft(1,ntau-i)
endif
enddo
ip=fp(ipat) ! see what's currently stored in fp(ipat)
if(ip.eq.-1) then
fp(ipat)=npindex
else
do while (np(ip).ne.-1)
ip=np(ip)
enddo
np(ip)=npindex
endif
return
end subroutine boxit
subroutine fetchit(reset,e2,ntau,i1,i2)
integer indexes(4000,2),fp(0:525000),np(4000)
integer lastpat
integer*1 e2(ntau)
logical reset
common/boxes/indexes,fp,np
save lastpat,inext
if(reset) then
lastpat=-1
reset=.false.
endif
ipat=0
do i=1,ntau
if(e2(i).eq.1) then
ipat=ipat+ishft(1,ntau-i)
endif
enddo
index=fp(ipat)
if(lastpat.ne.ipat .and. index.gt.0) then ! return first set of indices
i1=indexes(index,1)
i2=indexes(index,2)
inext=np(index)
elseif(lastpat.eq.ipat .and. inext.gt.0) then
i1=indexes(inext,1)
i2=indexes(inext,2)
inext=np(inext)
else
i1=-1
i2=-1
inext=-1
endif
lastpat=ipat
return
end subroutine fetchit