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T1 CrossConnect Installation & Operation Manual
Version 2
Example 2:
A problem occurs with the primary clock source and the DCS software initiates a switchover to the
alternate clock source. Given that the primary clock source is port 3 and the alternate clock source is
port 1, the requested clock is port 1, and these events occur:
1. The DCS requests a switchover.
2. The alternate clock source becomes the source of the reference clock (port 1).
3. A synchronization detection circuit compares the waveform on port 3 to the waveform on port 1.
4. When the signals of the actual clock source (port 3) and the reference clock source (port 1) are in
synchronization,
5. The alternate clock source (port 1) becomes the new system clock. Now the previous primary
clock source (port 3) becomes the new alternate clock.
Figure 2-1 shows a process flow of the two switchover examples to illustrate how the events during
each switchover parallel each other. Although the events that trigger the switchovers (event #1) are
different, a reference clock must always use the source of the requested clock to compare signals for
synchronization.
2-4
2 – Theory of Operation
GatesAir
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