Specifications

Installation and Operation Manual Chapter 1 Introduction
FCD-E1LC Ver. 1.0 Functional Description 1-9
When the main link is operated in the unframed mode, the framer is bypassed. In
this mode, the main link transparently transfers the data stream received from
one of the data channels. The appropriate data channel is automatically selected:
channel 1 for an FCD-E1LC with one data channel, and channel 2 for an FCD-E1LC
with two data channels.
Note that when the optional sublink operates in the unframed mode, it is also
automatically bypassed to the main link, but in this case all the other FCD-E1LC
ports are disabled.
Handling of National Bits
FCD-E1LC enables you to control the handling of the national bits, S
a4
through S
a8
,
in timeslot 0. You can select the utilization and state of each bit, in accordance
with the following options:
• Transfer of management traffic: when the inband management traffic is
carried in timeslot 0, the user can select the S
a
bits that will carry the traffic.
• Setting any S
a
bit to the desired fixed value, “0” or “1”.
LIU
The transmit path of the LIU includes an HDB3 coder, which converts the NRZ
transmit data stream provided by the E1 framer to the line code specified for use
on E1 links, and then generates the E1 transmit signal in accordance with
ITU-T Rec. G.703.
The receive path of the LIU recovers the received E1 signal and the associated
clock signal. The recovered clock signal is used by other FCD-E1LC circuits, and is
also applied on the clock bus. The recovered E1 signal is decoded by an HDB3
decoder, and sent to the receive path of the E1 framer in NRZ format.
The operating mode of the LIU receive path, DSU or LTU, is user-selectable.
The HDB3 decoder can provide performance statistics for evaluating line
transmission quality even when the CRC-4 option is not used, by collecting data
on the bipolar violations (BPVs) detected in the incoming signal.
Sublink Interface
The optional sublink interface has characteristics similar to that of the main link
interface. The only difference is in wiring: the transmit and receive pairs in the
sublink RJ-45 connector are reversed relative to the main link, thereby enabling
connection of equipment with standard balanced interface by means of a straight
(point-to-point) cable. Therefore, a different adapter cable, CBL-RJ45/2BNC/E1
(also offered by RAD), is needed to use the unbalanced interface.
Note