2
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Functional Design
NetXpress LX & CM-30R Installation & Operation Manual
Version 1.1
GatesAir, Inc.
2-15
Intraplex Products
Figure 2-6. Stream Timing Synchronization
This method of timing distribution can be very simple and efficient in cases where programming
streams are emanating from one master site to all the remaining sites. However, programming may
be generated at multiple sites within the network, and these program source sites may not all receive
program streams from the master site that can be used as timing sources (Figure 2-7). In this
example, Site A is the master timing source, but Site C does not receive a stream from Site A and is
unable to synchronize its outgoing stream to the rest of the network. As a result, the two streams
received at Site D utilize different synchronization sources and cannot be properly received and
decoded.
Figure 2-7. Streams with Different Synchronization Sources
There are two possible solutions to this situation.
1.
Receive a stream at site C from Site A solely for the purpose of synchronization (Figure 2-4). The
cost of this solution is the additional bandwidth required in the network end-link to site C.
2.
An alternative approach would be to utilize highly accurate external timing sources at Sites A and
C to achieve network synchronization. One example would be a Stratum 1 traceable timing signal
NetXpress LX
A
NetXpress LX
B
NetXpress LX
C
Internal Timing
Stream Timing
Stream Timing
NetXpress LX
D
Stream Timing
Sites B, C, and D use stream
timing to derive timing from
master Site A.
NetXpress LX
A
NetXpress LX
B
NetXpress LX
D
NetXpress LX
C
Internal Timing
Stream Timing
Internal Timing
Site D cannot process both
incoming streams because they
have different timing sources.
