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1991-12-31
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Recommendation R.100
Replace 2 and onwards by the following:
"2. Digital Path Link
2.1 64 kbit/s international digital transmission circuits are realized by PCM
time slots or via TDMA satellite systems. SCPC (Single Channel Per Carrier)
satellite systems provide 56 kbit/s channels. Primary groups 60 - 108 kHz in
conjunction with V.36 [4] modems may also be used.
2.2 64 kbit/s TDM link
2.2.1 Recommendation R.111, section 1 defines the telegraph TDM systems at
64 kbit/s.
2.2.2 Recommendations X.50 [5] and X.51 [6] set out the parameters of envelope
interleaving TDM systems at 64 kbit/s, which provide 0.6, 2.4, 4.8 and 9.6 kbit/s
tributary data channels. These data channels can be used to transfer the aggregate
signals of TDM systems at 0.6 kbit/s (Recommendation R.103),
2.4 kbit/s (Recommendations R.101, R.105, R.112 and R.111, 2), 4.8 kbit/s
(Recommendations R.102 and R.111, 2) and 9.6 kbit/s (Recommendation R.111, 2).
2.3 56 kbit/s TDM links are realized using envelope interleaving TDM systems
which are defined in Recommendations X.55 [7] and X.56 [8]. These systems provide
the same tributary channels as in 2.2.2.
2.4 Figure 1/R.100 shows a typical multiplex hierarchy.
* The R.103 remote multiplexer may be connected to an R.101, R.112 or an R.102
multiplexer. In this example, the eight remote link channels are included in
the 46 channels of the R.101 multiplexer.
FIGURE 1/R.100
Typical multiplex hierarchy
2.5 The capacities of 50 baud channels of 64 and 56 kbit/s TDM systems are
shown in Table 2/R.100.
TABLE 2/R.100
50 baud channel capacities of homogeneous TDM systems
┌─────────────────────────────────────────────┬───────────────────────────────┐
│ │ │
│ │maximum No. of 50 baud channels│
│ Recommendation No. of TDM systems ├─────────────┬─────────────────┤
│ │ │ │
│ │ transparent │ non-transparent │
├─────────────────────────────────────────────┼─────────────┼─────────────────┤
│ │ │ │
│ R.111, 1 (64 kbit/s) │ 240 │ - │
├────────────────┬────────────────────────────┼─────────────┼─────────────────┤
│ │ │ │ │
│ │20 x R.101 (2.4 kbit/s) │ - │ 920 │
│X.50 (64 kbit/s)├────────────────────────────┼─────────────┼─────────────────┤
│X.51 (64 kbit/s)│20 x R.112 (2.4 kbit/s) │ 300 │ 920 │
│X.55 (56 kbit/s)├────────────────────────────┼─────────────┼─────────────────┤
│ or │10 x R.102 (4.8 kbit/s) │ 300 │ 920 │
│X.56 (56 kbit/s)├────────────────────────────┼─────────────┼─────────────────┤
│ │20 x R.111, 2 (2.4 kbit/s)│ 160 │ - │
│ ├────────────────────────────┼─────────────┼─────────────────┤
│ │10 x R.111, 2 (4.8 kbit/s)│ 160 │ - │
│ ├────────────────────────────┼─────────────┼─────────────────┤
│ │5 x R.111, 2 (9.6 kbit/s) │ 160 │ - │
│ ├────────────────────────────┼─────────────┼─────────────────┤
│ │20 x R.105 (2.4 kbit/s) │ - │ 5120 (Note) │
│ ├────────────────────────────┼─────────────┼─────────────────┤
│ │80 x R.103 (0.6 kbit/s) │ - │ 640 │
└────────────────┴────────────────────────────┴─────────────┴─────────────────┘
Note - Virtual channels.
2.6 The characteristics of 64 and 56 kbit/s digital circuit interfaces are
described in Recommendations G.703 [9] and V.36 [4].
REFERENCES
[1] CCITT Recommendation - 9600 bits ber second modem standardized for use on
point-to-point 4-wire leased telephone-type circuits, Recommendation V.29.
[2] CCITT Recommendation - Transmission requirements of international voice-
frequency telegraph links (at 50, 100 and 200 bauds), Recommendation H.22.
[3] CCITT Recommendation - Performance characteristics of PCM channels between
4-wire interfaces at audio frequencies, Recommendation G.712.
[4] CCITT Recommendation - Modems for synchronous data transmission using
60-108 kHz group band circuits, Recommendation V.36.
[5] CCITT Recommendation - Fundamental parameters of a multiplexing scheme for
the international interface between synchronous data networks,
Recommendation X.50.
[6] CCITT Recommendation - Fundamental parameters of a multiplexing scheme for
the international interface between synchronous data networks using 10-bit
envelope structure, Recommendation X.51.
[7] CCITT Recommendation - Interface between synchronous data networks using
a 6+2 envelope structure and single channel per carrier (SCPC) satellite
channels, Recommendation X.55.
[8] CCITT Recommendation - Interface between synchronous data networks using
an 8+2 envelope structure and single channel per carrier (SCPC) satellite
channels, Recommendation X.56.
[9] CCITT Recommendation - Physical/electrical characteristics of hierarchical
digital interfaces, Recommendation G.703."
Recommendation R.101
1. Add the following note to Table 4/R.101 (The existing note becomes "Note 1"):
"Note 2 - The allocation of 50-baud channel 16 for maintenance purpose cancels the
possibility to set up 100-baud channel 16 and 200-baud channel 04."
2. Add the following note to Table 5/R.101 (The existing note becomes "Note 1"):
"Note 2 - The allocation of 50-baud channel 24 for maintenance purpose cancels the
possibility to set up 75-baud channel 24 and 150-baud channel 08."
3. Replace the word "numbering" for "allocation" in the headings of
Tables 3/R.101, 4/R.101 and 5/R.101.
4. Add the following to point 11.1:
"The implementation of this optional measurement should be such that the
error rate on the synchronizing bits is supervised continuously and an alarm is
issued when a preselected limit has been reached.
The alarm limits should be at least one faulty bit every 103, 104 or 105
bits.".