Specifications

Introduction
1-12 MP2100M-LS-2 Modules - Installation and Operation Manual
1
6 User Data
Bits
2 3 4 5 6 7 8
S Bit
(Status Bit)
F Bit
(Framing and
Housekeeping)
Envelope
Figure 1-7. ITU-T Rec. X.50 Envelope Structure
The resulting equivalent channels are listed in Table 1-2. Note that the user's
payload is 6/8th of the equivalent channel rate.
Table 1-2. ITU-T Rec. X.50 Equivalent Channels
Channel Rate Number of Channels in 64 kbps User's Payload
12.8 kbps 5 9.6 kbps
6.4 kbps 10 4.8 kbps
3.2 kbps 20 2.4 kbps
Referring to the byte-interleaved structure of figure 1-6, it is seen that a user's
channel of 9.6 kbps will repeat in every 5th envelope, a 4.8 kbps channel will
repeat in every 10th envelope, and a 2.4 kbps will repeat in every 20th
envelope. It is therefore convenient to view an ITU-T Rec. X.50
byte-interleaved multiplexer as a multiplexer that uses a repetitive structure
consisting of 20 envelopes, as shown in figure 1-8. The smallest repetitive
substructure is then of 5 envelopes. Note however that the frame
synchronization sequence remains unchanged and it repeats every 20 frames.
Envelope No.
1 2 3 4 5 6 7 8 9 1011121314151617181920 1 2
. . . . .
. . . . .
Repetitive Envelope Structure
Basic
Substructure
Figure 1-8. Repetitive Envelope Structure
Figure 1-9 shows the structure of a multiplexed signal that uses the 20-envelope
multiplexing model.