References - Ericsson CME 20 R6.1 Reference Manual

Synchronization
18.1

References

/GSM 05.10/
/JTC PCS/
/G.823/
18.2 Concepts
Locking
Synchronizing
Internal Source
Optional Reference
PCM reference
Hold-over Entered Time
Hold-over Expired Time
18.3 Functions
18.3.1 Synchronizing to the Reference Source
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.
18.3.2 Selection of Reference Source
In an RBS using the optional synchronization reference as reference
source, there are no reselection possibilities.
In an RBS where the executive reference is taken from the PCM
interface, PCM-A has to be usable as reference at startup.
If PCM-A is not usable as reference, a reselection of PCM-A as the
executive reference is performed when it becomes usable as reference
again.
126 (306)
GSM TS 05.10 revision 4.3.0
JTC(AIR) 940904-231R4 Technical
Specification of PCS 1900 by the PCS
1900 Joint Technical Committee
CCITT G.823, White Book
The process of acquiring a phase lock to
the references
The process of maintaining a phase lock
to the reference
An internal short-term stable oscillator
An optional frequency reference source
built into the RBS
A frequency reference extracted from the
PCM-network
The time before reporting a hold-over
mode, i.e. a fault is sent to the BSC
The maximum time in hold-over mode.
After this time, the synchronization
quality will not be guaranteed and the
BSC should disable the RBS so that radio
transmission ceases
© Ericsson Radio Systems AB
— All Rights Reserved —
EN/LZT 123 2697 R5A
1998-08-13