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4.4 Technical Details on GNSS, Antennas and Cables
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4.4
Technical Details on GNSS, Antennas and Cables
4.4.1
Antenna Cable
Length and Loss Considerations
Standard Antenna Cable
The standard antenna cable assembly included with the Model 1133A is constructed using a 15-
meter (50-foot) length of RG-6 type low-loss coaxial cable, terminated with male Type F connectors.
Optional lengths of RG-6 coax are separately available for longer runs; see Table 4.2, Cable Data
and Accessory Information.
Effects of Cable Parameters
To receive GNSS signals and properly operate the 1133A, the type and length of the cable are
important. Due to their effect on specific parameters described in the following paragraphs, any
changes to the length and/or type of antenna cable should be made carefully. Damaged cables may
also affect performance.
Cable Delay
Cable delay is the time required for the GNSS signal to travel from the GNSS antenna to the GNSS
receiver inside the Model 1133A. The velocity factor, the length and type of cable determine the
cable delay. In very precise laboratory applications it may be necessary to compensate for this
delay. However in the Model 1133A, used for phasor and frequency measurement of power systems,
it is not significant enough to require compensation as long as you stay within the cables mentioned
in Table 4.2.
Attenuation
Attenuation depends upon the cable length, and the loss per unit length. The total attenuation
must be limited to 21 dB (maximum) at the GPS L1 frequency of 1575.42 MHz. Loss up to 42 dB
can be accommodated with the separately available 21-dB in-line preamplifier (AS0044700).
DC Resistance
The cross-sectional area and length of the conductors in the cable determine the dc resistance.
Since power to the RF preamplifier in the antenna is supplied via the antenna cable, excessive dc
resistance will degrade performance.
Available Antenna Cables and Accessories for Longer Runs
Arbiter Systems offers longer antenna cables for use with the Model 1133A Power Sentinel when
the standard 15-meter (50-foot) cable is inadequate. For RG-6 cable runs greater than 250 feet, up
to 500 feet, Arbiter offers a 21-dB in-line amplifier, P/N AS0044700. A larger RG-11 style cable
is available (P/N WC0004900, 305-m / 1000-ft roll), that can be used for runs to 120 meters (400
feet) without the in-line preamplifier, or 240 meters (800 feet) with the AS0044700 amplifier.