Excalibur ISX 5312, Руководство по эксплуатации

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Defining Operating Parameters
4-7
4. The screen displays the current Transmit Clock setting and possible options.
Press the > button to display additional options. The options are
Intrn
(internal
timing); DTE1 , DTE2 , DTE3 , DTE4 (timing derived from the respective DTE
external clock input);
DS1a
,
DS1b
(timing derived from the respective
T-1 line). Press the button beneath the desired setting. The screen then displays
the revised setting.
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L D S U T x C l o c k = D T E 1
I n t r n D T E 1 D T E 2 D T E 3 >
L D S U T x C l o c k = D T E 2
I n t r n D T E 1 D T E 2 D T E 3 >
< >
5. Press the Escape button to return to the Configure Clock submenu.
The ISX 5312/5314 allows you to select the priority order of applicable fallback clocks
that can be used in the event the primary Transmit Clock fails. This parameter can also
be used to change the source of timing for the primary (order 0) clock. When the timing
is lost, the unit automatically switches to the fallback clocks in the designated order. If
all the selected fallback clocks fail, the unit automatically switches to internal timing.
When a higher-priority clock recovers for 20 seconds, the unit automatically switches to
that timing source if the Clock Tolerance parameter is disabled.
When the Clock Tolerance parameter is disabled, line clock failures are detected by LOS
and external clock failures are detected by a lack of transitions on the clock input. When
the Clock Tolerance parameter is enabled, the transmit clock source is compared against
an internal reference clock. The transmit clock source is declared invalid when it is out
of the user-specified range. (Refer to the "Clock Tolerance" section in this chapter for a
complete description.)
To select the priority order of the fallback clocks, follow these steps:
1. Press the button beneath
Order
.
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L I S X 5 3 1 4 C o n f i g C l k
S e l c t O r d e r
< >