User Manual

CSM System Time – GPS & HSO Verification – continued

PRELIMINARY 2

SC 4812ET BTS Optimization/ATP – CDMA LMF

July 1999

3-30

High Stability Oscillator (HSO)

The High Stability Oscillator (HSO) module is a separate full–size card

which resides in a dedicated slot in the lower half of the C–CCP shelf.

This is a completely self contained high stability 10 MHz oscillator

which interfaces with the CSM via a serial communications link. The

CSM handles the overall configuration and status monitoring functions

of the HSO. In the event of GPS failure, the HSO is capable of

maintaining synchronization initially established by the GPS reference

signal for a limited time

The HSO is basically a high stability 10 MHz oscillator with the

necessary interface to the CSMs. The HSO is typically installed in those

geographical areas not covered by the LORAN–C system and provides

the following major functions:

 Reference oscillator temperature and phase lock monitor circuitry

 Internal oscillator generates highly stable 10 MHz sine wave, and

routed to reference divider circuitry

 Reference divider circuitry converts 10 MHz sine wave to 10 MHz

TTL signal, which is divided to provide a 1 PPS strobe to the CSM

Equipment Warm–up

Allow the base site and test equipment to warm up for 60 minutes

after any interruption in oscillator power. CSM board warm-up allows

the oscillator oven temperature and oscillator frequency to stabilize prior

to test. Test equipment warm-up allows the Rubidium standard timebase

to stabilize in frequency before any measurements are made.

CSM frequency verification

The objective of this procedure is the initial verification of the Clock

Synchronization Module (CSM) boards prior to performing the rf path

verification tests. Parts of this procedure will be repeated for final

verification after the overall optimization has been completed.