CXR Larus 80-100-400
Issue 1, July 2006
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oscillator, results in a card alarm output to the 54560 Alarm Interface Card and
to the 54550 Information Management Card. A data link to the 54550 card
allows the 54523 card to report its status (tracking, hold, stand-alone, or failed)
as well as control, personality and, with DS1 only, sync messaging data.
5.6219 Clocks A and B
Each of the two 54523 cards in a redundant system drives a Clock A or B
differential clock bus to the ten output card slots. Each card also drives a hold
indicator bus. Selection of the A or B clock is done automatically by logic
circuitry on the output cards; it can be changed manually from a terminal
connected to the 54550 Information Management Card.
5.6220 External 5 or 10 MHz Signal
In addition to the DS1/E1 inputs, the external 5 or 10 MHz signal may also be
selected as a tracking input. Selection is done manually by TL1 or Menu user
command through the interfaces of the 54550 Information Management Card.
Once an external signal has been selected as the tracking reference, the clock
card will stay on it until the user issues a different command. If the signal is
bad during external signal tracking, the clock card will enter the HOLD mode
until the signal recovers. However, the clock card will not go back to tracking
DS1/E1 inputs unless told to do so by command issued via the 54550 card.
5.6221 Monitor
Jack
A front panel DS1/E1 monitor jack (-20 dB referenced to the input) provides
framed all ones at the clock output frequency. The CC/5 MHz/10 MHz monitor
jack is for the active input signal.
5.6222 One-wire
Interface
A one-wire interface communicates to the 54550 Information Management
Card that the 54523 is installed.
5.6223 Synchronization Status Messages (DS1 with ESF only)
When an SSM is received, the active 54523 clock card will reproduce it and
send it out via the output card. As an example, the received SSM is PRS and
its bit pattern is 0000010011111111 (refer to Table 5-A). The 54500 system
will transmit this message so that, at the output, the system will be able to
detect that the SSM equals PRS.
If the input DS1 is lost, the active clock card will go to holdover mode and then
output the SSM that is equal to its own stratum level. Removal of the input
DS1 causes the StarClock 200E system to act in the following sequence:
1. Display number 9 indicates LOS.
2. 54550 sends the LOS message to the terminal interface.
3. Clock card goes to HOLDOVER.
4. Output is STRATUM 2 SSM.
