Specifications

Installation and Operation Manual Chapter 1 Introduction
FCD-E1LC Ver. 1.0 Functional Description 1-15
• DTE1 – the data channel sends the receive data accompanied by the receive
clock, derived from the main system clock, to the user’s equipment
connected to the data channel, and accepts user’s data according to the
user’s equipment transmit clock.
• DTE2 – FCD-E1LC transmits and receives data according to the clock signals
provided by the equipment connected to the data channel. When using this
clocking mode, the main link clock is locked to the clock signal supplied by the
user’s data channel interface. The DTE2 mode is not available on channels
with X.21 interfaces.
FCD-E1LC provides a FIFO buffer for the data channel, to absorb timing
differences. FIFO size is generally automatically selected, however, in the DTE2
timing mode the user can increase the FIFO size beyond the automatically
selected value, to meet specific system requirements.
V.24 Data Channel Timing
The V.24 data channel operates only in the DCE timing mode.
Ethernet Port Timing
The timing of the Ethernet processing circuits is always derived from the main
system clock (“DCE” timing). This port cannot be selected as a timing source.
Diagnostics
FCD-E1LC has comprehensive diagnostics capabilities that include the following
types of loopbacks and tests:
• Main link:
 Local analog loopback
 Remote analog loopback
 Local digital loopback
 Remote digital loopback
 Inband-activated loopback in the desired timeslots (both transmission to
a remote unit, and activation/deactivation in response to an inband
loopback code)
 BER testing in the desired timeslots. To provide compatibility with other
BER testing equipment, the user can select the pattern used for the test
from a wide range of patterns, including standard pseudorandom
patterns.
• Sublink:
 Local analog loopback
 Remote analog loopback
 Local digital loopback
 Remote digital loopback