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<h1>Clock Synchronisation</h1>

<p>The Nokia PrimeSite offers one basic configuration, which
can be flexibly expanded with the BTS clock synchronisation. The PrimeSite
has an extension clock interface, which can be used to synchronise all PrimeSites
on cell or site. When several PrimeSites are synchronised, one BTS functions
as the clock source, the master, and the other BTSs follow its clock and act
as slaves. The master BTS transmits frame clock and frame number signals to
the extension clock lines while the other BTSs receive these signals to create
internal clock signals. The clock synchronisation is implemented by connecting
the BTSs with extension clock cables.</p>


<p>The BSC performs the clock synchronisation procedure and
assigns the clock parameter values defined by the operator to PrimeSites.
The clock recovery is performed if either the clock initialisation fails or
the BSC receives a clock synchronisation alarm. The clock recovery leads always
to a minimum configuration, that is, all PrimeSites except the BCCH PrimeSite
of the cell are blocked by the BSC. When setting the cell into the minimum
configuration, all the PrimeSites of the cell are configured to use their
internal clock. The minimum configuration is not recovered autonomously but
as a result of a user action.</p>


<p>By default the PrimeSite uses the internal clock for timing.</p>


<p>The extension clock interface is designed for multi-point
transmission on up to a 100m long chain. A longer distance between the first
and the last PrimeSite in the chain may cause synchronisation errors. The
extension clock lines have to be terminated at both ends of the chain by 120-ohm
resistor adapters. </p>
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