Symmetricom Time Server user manual Antenna Information

Site Preparation

2.1.3Antenna Information

Voltage Requirement and Signal Levels

TimeVault requires a 12 V antenna. Any antenna that does not support 12 V may be severely damaged if plugged into TimeVault.

The GPS Synchronized Receiver, integral to TimeVault, operates on the L1 (1575.42 MHz) signal and the C/A code (1.023 MHz bit rate) with a minimum signal level of –162.0 dBW and a maximum signal level of –137.0 dBW. The antenna system supplied is designed to provide the proper signal levels to the receiver with the cable length supplied.

Chapter 2: Installation and Start-Up

12 V GPS Antenna

Coaxial Cable

Threaded Cable

Housing

Use of a Splitter	Figure 2-1 Basic Antenna
	Components

To run multiple units with a single 12 V antenna, use a splitter. Do not use a BNC “T” connector, which doesn’t provide the proper voltage the unit needs to operate.

Lead-In Cable

The L1 GPS antenna is designed to operate with up to 200 ft (60.96 m) of RG-59 coax cable. The optional Down/Up Converter is designed to operate with up to 1,500 ft

(457.2 m) of RG-58 coaxial cable. For details and illustrations on cabling, see page 2-15.

2.1.4GPS Roof-Mounted Antenna Installation

When selecting a site for the standard outdoor antenna, find an outdoor location that provides full 360-degree visibility of the horizon. In most cases, this means locating the antenna as high as possible. Any obstruction will degrade unit performance by blocking the satellite signal or causing a reflection that cancels some of the signal. Blocked signals can significantly increase the time for satellite acquisition, or prevent acquisition all together.

Mast Mounting

Mast top mounting is the preferred mounting method and special brackets are provided to mount the antenna to a pipe or the peak of a building. The antenna mounting mast should be

2-inch (5.08-cm) water pipe or conduit. The mast must be rigid and able to withstand high winds without flexing. Guy wires may be used to stabilize a mast longer than 10 ft (3.048 m)

Multipath cancellation is caused by reflected signals that arrive at the antenna out of phase with the direct signal. Reflective interference is most pronounced at low elevation angles from 10 to 20 degrees above the horizon. You may

12 V GPS Antenna

Mast

Figure 2-2: Mast Mounting Illustration

6000-100Ch2.fm Rev. D TimeVault™ User’s Manual 2-13