User's Manual Part 1

Local GPS (RF–GPS) Antenna Cabling – continued

PRELIMINARY

1X SC480 BTS Hardware Installation, Optimization/ATP, and FRU

MAY 2004

3-12

Mounting Considerations

Table 3-8 lists the Local GPS Head requires specific mounting

considerations in order to properly observe the GPS satellites.

Table 3-8: Local GPS Antenna Mounting Considerations

n Consideration

1 The mounting pipe for the Local GPS Head should be mounted vertically with less than five (5)

degrees of tilt.

2 The Local GPS Head requires a clear view of the sky, preferably to within ten (10) degrees of the

horizon in all directions. The more sky that is observed increases the number of potential satellites

that can be tracked, resulting in better Local GPS performance.

3 During normal operation, the Local GPS Head continuously tracks a minimum of four (4) GPS

satellites. However, it is theoretically possible to operate the BTS by tracking only one (1) GPS

satellite. Motorola does not recommend tracking only one (1) GPS satellite unless there has been

an accurate site survey.

4 Place the Local GPS Head where RF obstructions of the sky are minimal. The “sky” includes

everything to within ten (10) degrees of the horizon in all directions. RF obstructions include

buildings, towers, natural rock formations, snow, foliage, and debris.

5 Separate the Local GPS Head from other radiating sources. Excessive RF energy can degrade the

Local GPS Head’s ability to observe the GPS satellites. The Local GPS Head receives on the GPS

L1 frequency of 1575.42 MHz and incorporates filters to minimize the effects of potential RF

interference, however, strong radiants can overwhelm the filters, thus degrading the units reception

capability.

6 The Local GPS Head is rated for ambient air temperatures in the range –40 to + 50_C, and has

ratings for humidity, shock, waterproofing, UV light resistance, vibrations, salt, fog, ESD, EMI,

and altitude.

7 If the overall length of the Local GPS Head to the BTS is greater than 50 feet, the cable style and

length should be determined by the site configurations. The maximum loss should be less than

4.5 dBm @ 1575 MHz for all cabling and connections between the Local GPS Head and the

frame.