Schmid Watson Przewodnik Instalacji Pobierz pdf (Strona 32)

SZ-DOC-W5-1.pdf LTU/NTU

Version: 1.5 Operating Manual

23 Revision: 2002-09-10

• Remote: The transmitting clock is the recovered remote clock, i.e. the same clock as the

receiving clock (115) at the V.35 and V.36 interface (contra-directional, circuit 114).

The clock mode to be used depends on the individual network configuration:

• nx64 kbit/s - nx64 kbit/s connection: First, it should be checked whether the equipment

connected to the nx64 port uses a transmitting 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.

As the contra-directional X.21 clock modes use only one clock, these configurations are

possible: nx64 port - nx64 port, nx64 port - remote, internal - remote.

• nx64 kbit/s - E1 connection: The clock mode can be selected as in the previous case.

It is recommended to have at least one clock reference. So one should not use remote clock

mode at both ends. You should not choose remote clock mode either if the remote modem is E1

and the E1 equipment connected to the remote E1 port uses loop timing (i.e. it uses the received

clock as transmit clock).

3.4.11 Clock Direction

For V.35 and V.36 interface types, the clock direction can be configured by the user. If

codirectional, Transmit Data 103 is sampled with Transmit Clock 113. If contradirectional,

Transmit Data 103 is sampled with Transmit Clock 114. It is recommended to use codirectional

transmit timing whenever possible, in particular for bit rates > 32 x 64 kbit/s.

3.5 Time Slot Mapping

Generally, the user interface time slots are mapped onto the DSL frame according to ETSI

TS 101 524. The time slots of the user interfaces are linearly mapped to the B-channels of the

DSL and vice versa. The number of time slots n from the user interface(s) must be less or equal

the number of B-channels (N). Unused B-channels are filled with all ones. After startup, the

complete mapping information of the units is mutually exchanged and used to set up the

demapping of the time slots.

Additionally, special mapping modes can be selected by configuration in order to make best use

of the available DSL bandwith for the respective application.

3.5.1 E1 to frE1 Time Slot Mapping

FrE1 Time Slots at User Interface 2, Slave Side

…

E1 Time Slots at User Interface, Master Side

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DSL Payload Sub-Block

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Schmid Watson Przewodnik Instalacji Strona 32