The optical interface can be connected to other fiber optical converters from Fibersystem as the 21-16xx (for X.21, RS.530, etc). or the 21-180 for balanced G.703. The 64kbps data is inserted and extracted from time slot 31 in the G.704 frame structure leaving the other time slots available for other usage. The converter adapts the data rate to the incoming E1 signal by a digital PLL or in a back to back configuration it can be set to use its internal reference.
The 21-170, Fiber optic G.703 E1 converter is intended to extend distance and to provide galvanic isolation for disturbance free insertion of 64kbps data into SDH/PDH 2Mbps G.703 connections by the use of the G.704 framing structure,
The converter is compatible with the FOT module in ABB’s teleprotection terminals 550/560 for connecting the terminals to higher order networks.
The 21-170 converter running of its internal clock can also be used to directly interconnect protection equipment over leased lines using electrical E1 modems as SHDSL and alike.
The ITU-standard “G.703 64kbit/s codirectional interface” describes a galvanic interface.
This interface.is commonly used by teleprotection equipment for connection to telecom multiplexers.
The 21-170 converts the codirectional interface signals to a proprietary fiber optic protocol used for example by teleprotection equipment from ABB.
G.703/704 E1 UnbalancedThe ITU-standard G.703 describes the physical and electrical characteristics of hierarchical digital interfaces at rates up to 140 Mbps.
G.704 describes frame structures on G.703 interfaces up to 45 Mbps.
E1 describes a galvanic G.703 interface with G.704 frames at 2048 kbps commonly used in telecommunication.
