User Manual

E -GPS (External -GPS) Chapter 4: E -GPS (External -GPS) R eplacement Procedures

E -GPS (External -GPS)

■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■

■

E -GPS Description

The E -GPS is located in the UBS Macro BTS frame and is mounted at the very top of the frame.

The E -GPS may be used instead of the optional Remote GPS (RGPS) head.

The E -GPS contains a GPS Receiver (GPSR) that requires connection to an external GPS RF

antenna signal. The E -GPS is considered to be local with respect to the UBS Macro BTS frame,

while the RGPS head is remotely located with respect to the UBS Macro BTS frame.

All cable connections to the E -GPS are made on the E -GPS front panel (see Figure 1 -4 E -GPS

I/O Details on page 1 - 31 ).

The E -GPS S SI -GPS connector is cabled to the S SI RGPS connector . This connection allows the

UBS Macro BTS frame to supply DC power to the E -GPS . In addition, control/data signals are

exchanged between the DMI controller and the E -GPS via this connection.

The E -GPS GPS -ANT connector is cabled to the external GPS RF antenna cable connector . This

coaxial cable connection allows the E -GPS to receive RF signals from GPS satellites as well as

supply DC power to the GPS RF antenna preampliﬁers.

The E -GPS receiver successfully tracks and acquires GPS satellites. The receiver detects GPS

RF signals and extracts a 1 Pulse P er Second (1PPS) timing signal. This 1PPS signal is applied

to the DMI controller via the S SI -GPS connector . The DMI controller contains an internal

Motorola Stability Oscillator (MSO) that is synchronized to the 1PPS timing signal and locked

to the GPS time base. If satellite tracking is lost or if the E -GPS fails, the MSO free runs, but

can maintain system timing for up to 8 hours.

If the UBS Macro BTS frame is equipped with an optional Quartz High Stability Oscillator

(QHSO), the DMI controller selects the QHSO as the backup synchronization source instead of

the MSO . The QHSO can maintain system timing for up to 24 hours.

System Impact/Considerations

P erforming this replacement procedure should not require BTS downtime or impact

call processing because of MSO or QHSO backup. However E -GPS downtime will

occur . And alarms will be reported.

4 -2 68P09283A64 -3

FOA SEP 2007