Installation Instructions

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COMPANY CONFIDENTIAL CENG0336_XE_nanoBTS_Installation_and_Test_Manual.doc
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6.8.7 Frequency Synchronisation Test
The Frequency Synchronisation test uses the nanoBTS’s NWL downlink receiver to
monitor one or more GSM RF channels, and if suitable BCCH carriers are found,
measure the frequency error of the local oscillator relative to the measured references.
The user can choose whether the frequency errors should be combined or reported
separately in the event that more than one BCCH carrier is found. The user can also
choose whether the nanoBTS should use the result of the test to adjust the local
oscillator to correct the error.
Note that a nanoBTS can only adjust its clock using this test if the Internal OCXO is
the active clock source. If the Internal OCXO is not the active clock source:
• If the nanoBTS being adjusted is a master, remove its 10 MHz input.
• If the nanoBTS being adjusted is a slave, either remove the cable from its TIB
In port, or use BTS Installer to temporarily disable the TIB Out of its master.
If the user attempts to perform a Frequency Synchronisation test with the “Adjust the
clock to correct the reported errors” option on nanoBTS that has an active external
clock source, BTS Installer displays an error message indicating that in order to
perform this test, the internal OCXO must be the active clock source.
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PRIOR TO CALIBRATION THE nanoBTS SHOULD BE POWERED UP
FOR A MINIMUM OF 10 MINUTES TO ALLOW IT TO STABILISE
Note that the nanoBTS may not be able to correct the frequency error in one go, so
you may need to re-run this test a few times to get the error down to a reasonable
level.
For further information on using the Frequency Synchronisation test to calibrate a
nanoBTS’s local oscillator, please refer to [CENG0336]. Note that in the event that no
BCCH carriers can be found, the nanoBTS’s local oscillator can be adjusted manually,
as described in section 6.5.5.10.
As with the BCCH Infor
mation test, if the BCCH Usage test has already been run, BTS
Installer automatically uses the results of that test to populate the ARFCN White List
for this test. When viewing the configuration of the test, you will see that the ARFCN
White list has automatically been selected as those detected with a BCCH. You can
override this if you wish.
To use this test select the Frequency Synchronisation tab on the left hand side of the
Network Listen window. Then, if you wish to view or change the configuration for the
test, select the Configure Test button located at the top of the screen.
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If BTS Installer finds that the Internal OXCO is the active clock source and tries to initiate the test, but in
the meantime an external clock source has become active, the nanoBTS rejects the test request and BTS
Installer displays an error message indicating “resource not available”.