Unit installation

Chapter 1 Introduction Installation and Operation Manual
1-16 Functional Description FCD-E1
User
DTE
FCD-E1/1
E1
Network
User
DTE
FCD-E1/2
FCD-E1/1
DCE
Timing
ML
Timing
DCE
Timing
ML
Timing
User
DTE
User
DTE
Loopback
Timing
DTE1
Timing
CH 2
CH 1
Master Timing
Source
DCE
Timing
Figure 1-4. Main Link Timing, Flow of Timing Signals in a Typical Application
When using the main link as the timing reference, the data port must use DCE
timing. However, DTE1 timing can also be used, provided the user’s equipment
connected to the data channels operates with loopback timing, that is, the user’s
equipment must lock its transmit clock to the receive clock provided by FCD-E1.
FIFO buffers are used on the data ports, to absorb small timing variations (jitter,
wander, etc.). FIFO size is automatically selected in accordance with the data
channel rate, as listed in Table 1-2.
The main link timing mode is particularly suitable for FCD-E1 units connected to
an E1 network which has an accurate master timing source (e.g., PTT or national
network), because it enables locking the timing of the equipment connected to the
FCD-E1 units to the network timing.
Sublink Timing Application
Figure 1-5 shows a typical application, which uses the sublink as the timing
reference source, and illustrates the flow of timing signals within the system.