Reference Manual

Synchronization
The outcome of this continuous supervision of the reference is either
that the reference is usable or not. The function terminates when
"Hold-over expired time" ends in "Hold-over state".
31.7 Locking to the Reference Source
Purpose
The function supervises the locking process and limits the time for
locking to the reference source.
Precondition and Initiation
The function is initiated when a locking attempt to a reference source is
made.
Description
The function checks that the control values for the internal source have
stabilised to within a range not including the highest and lowest values,
with a margin. Depending if the PCM interface or the Optional
reference source or another RBS is used as a reference, the following
criteria are used for evaluation of the locking process.
Locking to the PCM interface:
• PCM-reference presence (detected by physical interface)
•
Time, a time-out set at initiation
•
The value of the oscillator control signal
Locking to the optional reference:
•
Non-failure status of the optional sync. function
•
Time, a time-out set at initiation
•
The value of the oscillator control signal
Locking to other RBS:
•
ESB synchronization presence
•
Time; a time-out set at initiation
• The value of the oscillator control signal
The time-out, which is 6 minutes, is in both cases used to disqualify a
locking attempt that takes too long. A fault is sent to the BSC at time-
out, but the internal source will still try to lock an available reference.
Limited functionality is reached within 4 minutes from function
initiation. Calls can be established but performance criteria are not
fulfilled, that is to say, the risk of dropped calls is higher. The function
terminates when synchronization is established.
EN/LZT 720 0008 R1A
2001-06-26
253 (421)
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