User Manual

CSM System Time/GPS and HSO Verification – continued

3-42 1X SC4812T–MC BTS Optimization/ATP 5/21/04

DRAFT

High Stability Oscillator

CSM and HSO – 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.

HSO – The HSO is 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. Since the

HSO is a free–standing oscillator, system time can only be maintained

for 24 hours after 24 hours of GPS lock.

Upgrades and Expansions: HSO2/HSOX

HSO2 (second generation cards) both export a timing signal to the

expansion or logical BTS frames. The associated expansion or logical

frames require an HSO–expansion (HSOX). The HSOX accepts input

from the starter frame and interfaces with the CSM cards in the

expansion frame. HSO, HSO2, and HSOX use the same source code in

source selection (see Table 3-19).

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.

NOTE

CSM Frequency Verification

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

boards before performing the RF path verification tests. Parts of this

procedure will be repeated for final verification after the overall

optimization has been completed.

Null Modem Cable

A null modem cable is required. It is connected between the LMF

COM1 port and the RS232–GPIB Interface box. Figure 3-11 shows the

wiring detail for the null modem cable.