Harris ACS-163, Руководство по установке и эксплуатации

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ACS-160 Series & STL-160 Series T1 Multiplexer Installation & Operation 4 – Setup & Configuration
Version 2.11, August 2011
4-16 Harris Corporation
Intraplex Products
Figure 4-9. Multiple Systems Synchronized to Common Timing Source
4.4.6 Frame-Synchronized T1 Systems
Synchronized T1 systems have equal bit rates (frequencies) and are phase-locked, except for a limited
amount of jitter and wander. But synchronized T1 systems are not frame-synchronized, in general;
that is, systems in a synchronized network may transmit a given time slot at different times.
Frame synchronization is generally required whenever it is necessary to have precise control over the
relative delay times between multiple T1 circuits. For example, frame synchronization can be useful in
a mobile radio broadcast system using simulcasting (with multiple transmitter sites). To maximize
coverage, each transmitter in a simulcast system must transmit the same signal at a specific time
relative to the other transmitters. Frame synchronization allows fixed time delays to be added to
individual circuits in order to achieve the exact desired transmission delay for each circuit.
Multiple ACS-160 Series systems can be frame-synchronized by using a framed T1 signal generator
and using a CM-5RTD common module with time delay on each multiplexer at the hub site (Location 1
in Figure 3-10). The CM-5RTD module locks the frame generator of the common module to the
external signal.