5-1
Wireless Solutions
DualMode 800 Enclosure
Maintenance Manual
MTX08
Master Oscillator tests
5
Overview
Cell site transceivers require a stable reference in order to accurately produce
transmit carrier frequencies and to select receive frequencies.
The master oscillator produces this stable reference for the TRUs to ensure
that all channels operate on their assigned frequencies and do not interfere
with other channels.
The TRU shelf associated with the master oscillator output under test will be
out-of-service for the duration of the tests. It is good practice to use an unused
port for the frequency test if available.
Oscillator frequency specifications
High Stability Master Oscillator (HSMO): 4.8 MHz
±
1.2 Hz
The HSMO for digital operation must be tested using a Rubidium counter
reference or equivalent which provides a stable reference of <0.025 ppm.
The HSMO can also be tested using TRU carrier frequency measured with the
communications monitor. This requires measuring the frequency error of the
carrier in the expanded spectrum. The offset of 0.25 ppm (1.2 Hz/4.8 MHz)
translates to
±
220 Hz.
CAUTION
The HSMO is adjusted at the factory for frequency accuracy. If
the frequency test fails, do NOT adjust the unit, it must be
replaced with a new serviceable one.
Summary of Contents for DualMode 800
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Page 6: ...vi Publication history Nortel Networks Confidential 411 2051 500 Draft 00 01 November 1999...
Page 82: ...2 20 Periodic maintenance 411 2051 500 Draft 00 01 November 1999...
Page 90: ...3 8 Test equipment and precautions 411 2051 500 Draft 00 01 November 1999...
Page 100: ...5 6 Master Oscillator tests 411 2051 500 Draft 00 01 November 1999...
Page 106: ...6 6 Antenna and transmission line tests 411 2051 500 Draft 00 01 November 1999...
Page 116: ...8 4 Alarm Control Unit ACU tests 411 2051 500 Draft 00 01 November 1999...
Page 138: ...10 2 ICRM tests 411 2051 500 Draft 00 01 November 1999...
Page 200: ...12 10 Enclosure maintenance 411 2051 500 Draft 00 01 November 1999...
Page 208: ...A 8 Appendix A Frequency table 411 2051 500 Draft 00 01 November 1999...
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