Description; General Description - Toshiba G1IF1 Instruction Manual

3. Description

3.1 General Description

Figure 3.1 illustrates the operation of the Optical interface unit. The GRL100 relay and the
telecommunications multiplexer are illustrated to facilitate the explanation.
The G1IF1 unit provides three fibre optic connectors. The transmitter / receiver pair TX/RX
connect to the GRL protection signalling channel. The clock transmitter CLK can be used to
transmit the CCITT-G703-1.2.3(1.2.2) or X.21 timing signal, although it is not required in
applications such as this, where the receive signal from the G703-1.2.3(1.2.2) or X.21 is
synchronized to the clock signal. The CLK is not used for the CCITT-G703-1.2.1 interface. An
additional connection point, labelled SPARE (not shown in Figure 3.1), can be used for fitting of
a spare fibre optic cable.
Optical to electrical and electrical to optical conversion is performed on the transmit and receive
signals from the GRL100 relay respectively. CMI type encoding is used for the optical signals.
CMI encoding always results in a 50% duty factor, making the signals easy to check during
commissioning.
Code conversion is performed for connection to the CCITT-G703 or X.21 interface. G703 or
X.21 is a synchronous interface, and provides a 64kHz timing signal, which the G1IF1 uses for
synchronisation. The connections to the G703 or X.21 interface use balanced drivers and
receivers in accordance with the G703 or RS422A/V.11 standard.
GRL100
Serial
Comms
Interface
Sync.
50/125m
62.5/125m
Fibre
G1IF1
Code
E/O O/E
Conversion
TX RX
E/O
O/E
CLK
CLK
Code
E/O O/E
Conversion
RX TX
+
Auxiliary DC
Supply
-
Figure 3.1 Operation of G1IF1 Unit
 5 
64kHz
()
Sync.
CCITT G703
Cable
(): not required for CCITT G703 1.2.1.
DC/DC
Converter
6 F 2 S 0 7 5 5
Telecomms
Muliplexer