_____________________________________________________________
__________________________________________________________
5−
41
Card that the 54593 is installed.
5.9223 Synchronization Status Messages (DS1with ESF only)
When an SSM is received, the active 54593 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.
5.9224 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 54500 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 1 SSM.
5. 54550 sends the current SSM status to the terminal interface. (For the
54593, it is Stratum 1.)
A GPS signal is considered a PRS so, if the clock card is tracking a GPS
input, the clock will send out a PRS SSM.
If the active clock card receives an SSM that is lower than its own stratum
level, it will treat the case as LOS.
If there is no SSM in the DS1 input, the clock will send out STU (SSM
unknown), e.g. ESF with no code word or SF.
If one input DS1 has a higher level of sync status, the clock card will
automatically switch to input the higher level DS1.
During input tracking, if the input SSM changes, the clock card will change its
output SSM accordingly within 5 seconds.
Before the clock card is stabilized, such as in the Free Run or Acquire 1 state,
the active clock will output a DUS ("Do not use") SSM. This is during initial
startup. After the startup period, the SSM described above will be generated
or passed through.
If a command is executed for SSM on the standby clock card, the SSM
message will be STU. In this case the message should be ignored.
5.9225 Power
An on-card power converter provides the necessary circuit voltages from the
diode-combined A and B -48 volt battery supplies. The on-card fuse, if it
blows, lights the red FAIL LED and provides battery to the Fuse Alarm bus
connecting to pin 10 on the backplane terminal strip TB1. Nominal power
input is -57 Vdc to -42 Vdc.
NOTE:
Содержание 54500-16
Страница 7: ...This page is intentionally left blank...
Страница 28: ..._______________________________________________________________ CXR Larus 80 100 400 Issue 2 July 2006 2 3...
Страница 29: ...CXR Larus 80 100 400 2 4 Issue 1 July 2006 ______________________________________________________________...
Страница 30: ..._______________________________________________________________ CXR Larus 80 100 400 Issue 2 July 2006 2 5...
Страница 31: ...CXR Larus 80 100 400 2 6 Issue 1 July 2006 ______________________________________________________________...
Страница 39: ...This page is intentionally left blank...
Страница 205: ...__________________________________________________________ 5 77...
Страница 214: ...AB 2 This page is intentionally left blank...