3: Installation And Set-Up; Installing The Gps Antenna; Selecting A Gps Antenna Site - Symmetricom XLi IEEE 1588 User Manual

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3: Installation and Set-up

In a nutshell:
• Install the GPS antenna outdoors, run the cable, and connect it to the XLi's GPS receiver.
• Make the following connections to the XLi (all cables supplied):
- From the network to the NET port (for access to the command line and web interfaces).
- From an AC outlet to the XLi's AC power supply.
• Configure the network settings of the XLi's standard network port.
• Configure the network settings of the XLi's IEEE 1588 network port.

Installing the GPS Antenna

Precise Time Protocol (PTP) grandmasters are typically synchronized to International Atomic Time (TAI).
To accomplish this, the user sets up the GPS antenna, connects it to the GPS receiver in the XLi IEEE
1588 Clock, and configures GPS as its primary reference source. When the XLi IEEE 1588 Clock locks
to the GPS reference source, it computes TAI and synchronizes the PTP grandmaster (the IEEE 1588
card). When the PTP grandmaster is synchronized to the XLi IEEE 1588 clock it starts operating,
sending out PTP Sync and Follow_Up messages and responding to PTP requests.

Selecting a GPS Antenna Site

Select a site outdoors that...
• Is the highest point available
• Offers a full 360° view horizontally, to within 10° vertically of the horizon
• Is higher than neighboring buildings/obstructions
• Is protected from strong radio frequency (RF) and microwave transmissions
• Is set away from RF-reflective surfaces that cause multipath interference
• Is set 3 ft. (1 m) away from other GPS antennas
• Is within the maximum GPS antenna cable length from the XLi
Typically, this site is on the roof of the building.
Avoid...
• Mounting the antenna between tall buildings or next to walls and equipment
• Exceeding the maximum cable-lengths specified for a particular cabling arrangement.
• Patching multiple cables together to make a single cable run
• Running the cable through bulkheads and along side high-energy cables
• Crimping or damaging the cable
• Mounting within 15 meters/yards of lightning rods, tower, or structures that attract lightning
XLi IEEE 1588 Clock
997-01510-03, Rev. C, 12/12/2006
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