Specifications

Watson TDM
Operating Manual
Watson-TDM-Manual-W.doc
Version 2.0-01
3-18
Revision: 2008-02-07
cuit 114). This clock mode should be used for multiservice operation (simul-
taneous use of E1 and nx64 kbit/s).
• Internal: The transmit clock is generated from the internal reference clock
(contra-directional, circuit 114).
• Remote: The transmit clock is the recovered remote clock, i.e. the same clock
as the receive clock (115) at the V.35 and V.36 interface (contra-directional,
circuit 114).
The clock mode to be used depends on the network configuration. First thing to
check is whether the equipment connected to the nx64 port uses a transmit clock
output or input. In the first case, the co-directional nx64 port mode can be used.
In the latter case, one of the contra-directional clock modes should be used. The
internal clock mode should be suitable in most cases, the remote clock can be
used if the receive and transmit clocks have to be equal.
The contra-directional X.21 clock modes use only one clock signal. Therefore the
following configurations are possible: nx64 port - nx64 port, nx64 port - remote,
internal - remote.
It is recommended to have at least one clock reference. Configurations with re-
mote clocks on both ends must be avoided.
Remote clocking will also lead to problems if the remote modem has an E1 inter-
face and the E1 equipment connected to the remote E1 port uses loop timing (i.e.
it uses the received clock as transmit clock).
3.5 Timeslot Mapping
Generally, the user interface timeslots are mapped onto the DSL frame according
to ETSI TS 101 524. The timeslots of the user interfaces are linearly mapped to
the B-channels of the DSL and vice versa. Unused B-channels are filled with all
ones. After startup, the complete mapping information is exchanged between
STU-C and STU-R.
3.5.1 E1 mappings
E1 mapping is determined by the configuration of the E1 interfaces on STU-C
and STU-R.
Application
User interfaces
Mapping rule
TS 101 524
TS0/TS16 options
(See Table 3-6)
2 Mbps transparent
G.703 – G.703
Unaligned D2048S (none)
ISDN PRA
G.704 – G.704 PRA
Aligned D2048S (none)
2 Mbps framed
G.704 – G.704
Aligned D2048S
MP 4
MP 5
Fractional E1
G.704 – G.704
Aligned fractional D2048S
MP 0 MP 3
MP 1 MP 4
MP 2 MP 5
Table 3-5: E1 mappings