User's Manual Part 2

CSA System Time – GPS & HSO/MSO Verification
MAY 2004 1X SC480 BTS Hardware Installation, Optimization/ATP, and FRU 6-43
PRELIMINARY
Clock Synchronization and
Alarm (CSA) Sub–system
Description
Overview
The primary function of the CSA card is to maintain CDMA system
time. A GPS receiver provides the primary timing reference for all
CDMA BTS’s During normal operation, the CSA clocking outputs are
phase locked to the GPS receiver timing reference. The CSA supports
either an on–board GPS receiver module (RF GPS) or Remote GPS
(RGPS) receiver. The RGPS receiver consists of a combined GPS
receiver and antenna witha digital interface to the CSA.
Backup Timing References
Timing signals from the High Stability Oscillator (HSO) or Medium
Stability Oscillator (MSO) are used in the event that the primary (GPS)
reference should become unavailable. The HSO or MSO clock is
calibrated against the GPS timing signal when a valid GPS timing signal
is available to provide the longest possible backup timing performance.
The CSA continuously monitors each available timing reference and
utilizes the most suited reference to maintain system synchronization.
Timing Source Fault Management
Fault management has the capability of switching between the GPS
synchronization source and the HSO/MSO backup source in the event of
a GPS receiver failure. During normal operation, the CSA selects GPS as
the primary timing source (Table 6-20). The source selection can also be
overridden via the WinLMF or by the system software.
Front Panel LEDs
The status of the LEDs on the CSA boards are as follows:
S Steady Green – CSA locked to GPS.
S Rapidly Flashing Green – Standby CSA locked to GPS.
S Flashing Green/Rapidly Flashing Red – CSA OOS–RAM attempting
to lock on GPS signal.
S Rapidly Flashing Green and Red – Alarm condition exists. Trouble
Notifications (TNs) are currently being reported to the GLI.
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