Reference Manual

Synchronization
Synchronizing The process of maintaining a phase lock
to the reference
Internal Source An internal short-term stable oscillator
Optional Reference An optional frequency reference source
built into the RBS
PCM-reference A frequency reference extracted from the
PCM-network
External Synchronization Bus (ESB) A bus for distribution of
synchronization information between
RBSes in an RBS cluster
RBS cluster Two or more RBSes connected together
via an External Synchronization Bus
31.3 Synchronizing to the Reference Source
Purpose
The short-term stable oscillator built into the RBS needs to have a long-
term stable synchronization reference. The function provides the RBS
with the long-term synchronization source.
Precondition and Initiation
The function is initiated by two separate events:
• Synchronization established
•
When synchronization is re-established after hold-over operation
Description
The RBS has its own short-term stable oscillator; this internal source is
locked to the reference source. The generated frequency is used for
both RF frequency and for clocking of the timebase counters (see /
GSM:05.10:3/ and /JTC PCS:7–1/). The same source is used for all
carriers.
Termination
The function is terminated by three separate events:
1. The executive reference source is considered faulty by the
supervision function.
2. The control values of the RBS short-term frequency source of the
TU are persistently at limit values.
3. Reconfiguration of TF mode to Slave.
Note: It is not possible to change TF mode to Slave in enabled
state.
Operational Conditions
Synchronization is reached as noted below from function initiation.
EN/LZT 720 0008 R1A
2001-06-26
249 (421)
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