Furuno FELCOM 12 Service Manual page 39

The first 64 symbols of convolutional encorder output go to column 2, rows 0 to 63.
The next 64 symbols to column 3, rows 0 to 63 and so on.
The interleave block is transmitted on a row by row basis. The symbols in a row are
transmitted in asccending order of column position; that is, the two indentical unique
word symbols are transmitted first. However, rows are not transmitted in a sequential
order; they are transmitted according to a permuted sequence. If the rows in the
interleave block are numbered from i = 00 to i = 63 sequentially and the transmitted
order is from j = 0 sequentially through to j = 63; then, i and j are related by
i = (j × 39) modulo 64
1 st output j = 0 : i = (0 × 3S) modulo 64 = 0
2 st output j = 1 : i = (1 × 3S) modulo 64 = 39
3 st output j = 2 : i = (2 × 3S) modulo 64 = 14
Modulo 64 is the remainder of division by 64.
0
Row
1
2
62
63
row
25
Last frame
(
Preambling
The SES message channel is quasi–continuous therefore a preamble is added to aid
acquisition. The maximum message length is 32k bytes (about 32000 characters), as
about 50 frames can be sent consecutively.
n frame
(max : 50)
DATA
Column
0 1 2....................................161
1 65
2 66
3 67
63 127
64 128
.................
)
Figure 2-10 Permuting
UW ...............
Figure 2-11 Preambling
10177
10177
10177
10239
10240
2nd frame 1sd frame
10240bits 128bits
DATA UW DATA UW Preamble
clock regeneration : carrier recovery : 128bits
64bits all = 1
2-8
Permute Matrix
row row
39 0
1st frame
( )