Specifications

X723-300151 1-8 Issue 2
this does not affect the detection of 1 in 10
-3
error rate required for line service monitoring.
1.2.3.4 Synchronisation Options
The Series 3000 can be synchronised to a 2MHz or two 8KHz, known as
8k1 and 8k2, internal clock busses which are generated by certain channel
cards by recovering a phase locked clock from external interfaces. Access
to the 2MHz clock bus is fully controlled by the system controller.
However, access to the 8KHz busses are not. This is controlled by link
selection on the channel cards. Thus, care should be taken to ensure only
one channel card is connected to each of the 8KHz clock busses at any one
time. The Dual LIU supports the 2MHz clock bus which allows the
multiplexer to be synchronised to a PCM stream or external G.703 clock.
A prioritised list may be set up to give a primary sync source plus 4
fallback sources. The lowest priority source is always the internal free-run
oscillator. All clock sources are checked for frequency, and internal timers
may be invoked to avoid spurious switching between intermittent sources.
Sync sources from the PCM line signal recovered timing are also qualified
against various line signal fail options.
Note: A PCM line signal should not normally be used as the sync source if
it has its fault logging inhibited since failure of the line will not be
reported.
1.2.3.5 Alarm Event Options
An 'Alarm Event' may be used to trigger a change of configuration in
response to failure of either the incoming data paths or to a failed channel
card. These are used to provide automatic re-routing of services affected
by any failures.
For each multiplexer configuration each alarm event source can be
programmed to run a different multiplexer configuration, in the event of
failure, allowing recovery plans to be set-up for multiple failures.
1.2.3.6 Configuring Channel Cards
Channel cards in each port are identified by a letter e.g. P1A, (Port 1 card
A), P3G (Port 3 card G). Each channel card can support up to four
independent circuits numbered 1 to 4 e.g. P4D2 (Port 4 card D circuit 2).
Some channel cards can provide eight circuits and circuit allocation is
described in the relevant Equipment Manual.