Canon FACSIMILE BASIC 2000 Service Manual page 209

C
12
F
11
D A
10 11
E G
10 13
C B
C
8 13
4
F H F
1 8 3
A A
D
1 3
14
E
G
14
15
C B C
9 15 5
H
F F
9
0 2
A D A
0 2
12
E
12
G
11
C
B 13
11
F
10
A
10
Fig. 5-56 Mapping Rules in Trellis Coding (1)
If we focus on only expression by A to H regarding these 128 signal
points, of points A to H, four respective points A, B, C and D will be
selected under the condition Y0n=0. If the condition Y1n=0 is added to
each of these points A, B, C and D, the signal points to be selected will be
limited to two points, A and C. Further, of points A and C, A will be
selected if Y2n is 0, and C will be selected if Y2n is 1, and finally one of A
to H will be determined. Fig. 5-57 shows the finally selected point as a
large dot. If we focus on only the 16 points relating to point A selected
here, it can be seen that the minimum distance between each of the 16
points will be mapped to become twice the root extraction of 2 of the min-
imum distance between each of the 128 points.
G3 FACSIMILE COMMUNICATIONS
D
D
0
1
G
E G E
0 9 1
B C B
9 14 8
F
H F H
12 15 14
D A D
2 15 3
E G E G
2 5 3
B
C B
5
6 4
H H F
F
6
4 7
D
D
6 A
7
7
G
E
E G
7
6
7
B
7 C B
6
7
F
H
F
H
6
7
5
D A D
6 5
4
E G E G
4 3 5
B
3 B
C
2
15
H F H F
13 14 15
D
D A
9
8 14
E G E G
8 1 9
B
B
0
1
8
C
10
H
13 10
A D
13 11
E G
4 11 12
C B C
2 12 0
H H
F
5 2 9
A
D A
5
15 9
E G
6 15 14
C B C
3 14 1
H
F H
4 3
8
A D A
8
4 13
E G
2 13 10
C B
11 10
H
12 11
A
12
0
5–67
1
2
0
3
4
1
5
6
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