User manual

Chapter 2 Installation
28
Clocking Modes
There are three clocking schemes for the FIB1-DATA converters, shown below.
Int. Recovery
Ext. Recovery
Transparent Transparent
Figure 2-13 FIB1-DATA Clocking Modes
All models of the FIB1-DATA have a physical interface which is DCE. A
crossover cable is required when acting as a DTE device. In the first example, the
units act as 'Fiber Modems' with the internal clocking unit acting as a master time
source and the remote or loop unit recovering timing from the fiber side. In this
configuration, both units are acting as DCE.
In the second example, an external clock is received at one unit and the clock is
passed to the remote for recovery via the fiber. In this scheme, the left side unit acts
as a DTE and a crossover cable is required. The right hand unit recovers clock from
the fiber and acts as a DCE.
In our last example, transparent clocking is employed; the transmit clock on one
side is used as the source for receive clock on the other. In this scheme the units may
act as DCE or DTE depending on the cable used.
Fiber
TCTC
RC RC
Fiber
TC
RC
ETC
Fiber
ETC RC
ETC RC