E1 Input Module Alarm Modes - Symmetricom SSU-2000 User Manual

Although MTIE is continuously calculated against both clocks, MTIE alarms are
logged only if the measurements against the currently selected clock violate one of
the MTIE alarm masks.
TDEV Calculation
The Input module automatically (without user intervention) calculates TDEV (the
measurement of the frequency components in a series of phase readings) for all its
inputs and reports on the past 24 hours of TDEV history. TDEV is retrieved on hour
boundaries, though the stop time used may be current time.
Reported time periods include: 0.05, 0.10, 0.30, 0.60, 1.0, 2.0, 3.0, 6.0, 10.0, 30.0,
60.0, 100.0, 300.0, 600.0, 1000.0, 3000.0, 6000.0, and 10000.0 seconds
The E1 Input module also contains provisions for zeroing the phase readings for
one channel in response to a command from the Communications module. Once
the phase is zeroed, all subsequent phase measurements are expressed in terms of
how much they differ from the reading at the time the phase was zeroed.
Zeroing the phase invalidates all past phase averages, TDEV, and MTIE.
Sync Status Messages
The E1 Input module reads and processes Sync Status Messages (in accordance
with specification ITU-T Composite Clock (CC) for E1 signals), to determine the
traceability of inputs. This traceability information is then used by the Clock modules
in selecting a reference signal and embedded into the system's outputs. For E1
inputs, an SSM is valid if three consecutive matching SSMs are received.
SSM Selection Criteria
If the E1 Input module is configured for provisioned mode, it will use the provisioned
SSM. If configured for automatic mode, the Input module uses the most recent valid
SSM. If a valid SSM is not received, the module uses the provisioned SSM.

E1 Input Module Alarm Modes

The E1 Input module responds to various alarm conditions according to user-set
alarm levels. Each level is associated with a set of actions as follows:
Table 7-1. E1 Input Module Alarm Modes
Alarm Mode
IGNORE Do nothing
REPORT Do nothing
MINOR Generate event message
12713020-002-2 Revision F.01 – January 2007
Action
Cannot be elevated to a higher severity level
Cannot be elevated to a higher severity level
Elevate to Major if the alarm condition persists
beyond the user-set elevation time limit
Chapter 7 Input Module Reference Data
1-Port and 3-Port E1 Input Modules
Alarm Elevation
SSU-2000 User's Guide 163