RUGGEDCOM RX1100
Installation Guide
Chapter 3
Communication Ports
GPS Antenna Installation Recommendations
25
Section 3.8.3
GPS Antenna Installation Recommendations
The signals received from the GPS satellite network are at a frequency of 1575.42 MHz with a minimum power
of -162 dBW. The GPS antenna must have a clear view of the sky in order to receive the low power signals and
track the maximum number of satellites. Rooftops or other structures clear of obstructions and with a clear view
of the horizon are ideal.
Elements of a typical GPS antenna system include:
• Active GPS Antenna (required)
• Coaxial cable to connect the elements (required)
• Lightning arrestor (optional)
• Line Amplifier or Filter (optional)
To establish proper GPS signal reception, the overall system of antenna, cabling, lightning arrestor, line amplifier
and filters requires a relative gain which should be greater than 5 dBi but less than 18 dBi (to avoid signal
saturation at the receiver input).
The following sections describe each component in the GPS antenna system in more detail:
•
Section 3.8.3.1, “GPS Antenna”
•
Section 3.8.3.2, “Antenna Cabling”
•
Section 3.8.3.3, “Lightning Considerations”
•
Section 3.8.3.4, “Line Amplification and Filtering”
Section 3.8.3.1
GPS Antenna
There are two major types of GPS antenna: passive and active. A passive antenna requires no power and is
an option when signal strength is not a concern. An active antenna has a built in Low Noise Amplifier (LNA)
to increase the strength of the signal, and to compensate for the signal loss in a long cable connection. Active
antennas are used when the antenna input is connected to the receiver through a coaxial cable (usually longer
than 3 m) or any high loss transmission path.
NOTE
• The PTP card’s GPS input provides 5 VDC at up to 10 mA to power the antenna.
• Best results can be achieved with a total gain of 16 dB (includes antenna gain, cable loss, lightning
arrestor loss, line amplifier gain and filter loss) at the antenna input.
The PTP Card requires an active antenna with the following specifications:
Characteristic
Active Antenna
Polarization
Right-Hand Circular Polarized
Receive Frequency
1.57542 GHz ± 1.023 MHz
Power Supply
5 VDC
DC Current
< 10 mA at 3 VDC
Antenna Gain
Select antenna gain based on system configuration
