User's Manual

CSM System Time - GPS & LFR/HSO Verification68P09255A69-3

Aug 2002

1X SC4812ET Lite BTS Optimization/ATP Software Release 2.16.1.x

PRELIMINARY

3-39

Timing Source Fault Management - Fault management has the

capability of switching between the GPS synchronization source and the

LFR/HSO backup source in the event of a GPS receiver failure. During

normal operation, the card in slot CSM 1 selects GPS as the primary

timing source (Table 3-24). The source selection can also be overridden

via the LMF or by the system software.

Low Frequency Receiver/

High Stability Oscillator

General

The CSM and the LFR/HSO - The CSM performs the overall

configuration and status monitoring functions for the LFR/HSO. In the

event of GPS failure, the LFR/HSO is capable of maintaining

synchronization initially established by the GPS reference signal.

LFR - The LFR requires an active external antenna to receive

LORAN-C RF signals. Timing pulses are derived from this signal,

which is synchronized to Universal Time Coordinates (UTC) and GPS

time. The LFR can maintain system time indefinitely after initial GPS

lock.

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: LFR2/HSO2/HSOX

The LFR2 and HSO2 (second generation cards) both can export a timing

signal to other BTS frames located at a site. These secondary frames

require an HSO-expansion (HSOX) module whether the primary frame

has an LFR2 or an HSO2. The HSOX accepts input from the primary

frame and interfaces with the CSM cards in the secondary frames. LFR

and LFR2 use the same source code in source selection (Table 3-24).

HSO, HSO2, and HSOX use the same source code in source selection

(Table 3-24).

NOTE

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

minutes after any interruption in oscillator power. CSM card

warm-up allows the oscillator oven temperature and oscillator

frequency to stabilize prior to test. Test equipment warm-up

allows the Rubidium standard time base to stabilize in frequency

before any measurements are made.