Installation Instructions

BTS Configuration – continued

DEC 2000

7-19

SCt300 BTS Hardware Installation, ATP and FRU Procedures

PRELIMINARY

The HSO must be installed with GPS tracking for at least

24 hours before the HSO can provide 24 hours of backup

for CDMA system time synchronization.

NOTE

BTS

The BTS uses a Digital Phase Locked Loop (DPLL) to track the RGPS

and/or HSO and generate a 19.6608 MHz CDMA timing reference. This

timing reference, in conjunction with Time Of Day information provided

by the RGPS, allows the BTS to synchronize to CDMA system time. A

2 Second reference is also generated by the BTS to allow alignment of

Pilot offsets for the BTS and external test equipment. Both the 19.6608

MHz (19 MHz) and 2 Second (2 Sec) references are available via SMA

connectors located in the Diagnostic Access Area.

In order for the DPLL to begin the RGPS tracking process, the RGPS

must be tracking GPS satellites. In order for the DPLL to begin the

HSO tracking process, the BTS must be powered up (warmed) for at

least 15 minutes.

The DPLL status is defined as being in one of five states: Init, Warm,

A1, A2 and TK.

S The Init state is the starting state of the DPLL.

S The Warm state is the condition during the 15 minute BTS warm up

time.

S The A1 and A2 states are acquisition states when the DPLL is

adjusting the 19.6608 MHz frequency based on the available reference

sources (RGPS or HSO). Under normal operating conditions, the

acquisition states last about 5 minutes.

S The TK state is the DPLL tracking state and is entered at the end of

the acquisition states. The TK state is required for performing ATP.

Synchronization Configuration

The Sync button in the Diagnostic Access Area is used to toggle the

RGPS or HSO as the primary timing reference for the BTS. If the

External indicator in the Diagnostic Access Area is illuminated, the BTS

expects an RGPS to be present for use as the primary timing reference.

If the External indicator is not illuminated, the BTS will use the internal

HSO as the primary timing reference.

Use the procedure in Table 7-8 to verify and, if necessary change the

BTS Sync mode.