Gps Antenna Installation - FreeFlight ADS-B FDL-978 Series Installation Manual

ADS-B FDL-978 Series and
Lite Series Installation Manual
Document No. 87343 Rev F
Consider moving the FDL-978 Series and FDL-978 Lite Series closer to the antenna to minimize
the losses in the antenna cable subject to the limits identified above.
The following table is a guide to the minimum and maximum usable lengths of some common
cable types. Actual cable loss varies between manufacturers and the table is based on typical
data. Use the table as a guide only and refer to the manufacturer's data sheet for the specific
cable chosen to calculate the minimum and maximum lengths.
Cable
RG-174
RG-316
RG-400
RG-142
RG-393
When routing the cable, ensure the following:
•
Route the cable away from sources of heat.
•
Route the cable away from potential interference sources such as ignition wiring, 400Hz
generators, fluorescent lighting, and electric motors.
•
Allow a minimum separation of 12 in (300 mm) from an Automatic Direction Finder
(ADF) antenna cable.
•
Keep the cable run as short as possible.
•
Avoid routing the cable around tight bends.
•
Avoid kinking the cable even temporarily during installation.
•
Secure the cable so that it cannot interfere with other systems.

2.11 GPS Antenna Installation

Shadowing by aircraft structure (and in some cases by rotorcraft blades) can
adversely affect operation of the Global Navigation Satellite System (GNSS)
equipment.
The antenna should be installed according to the manufacturer's instructions.
Selecting appropriate GPS antenna locations is critical to the proper performance of the FDL-
978 Series and FDL-978 Lite Series. The following considerations should be taken into account
when selecting the Antenna location.
1. Typically, a GNSS antenna is located forward or aft of the wings on top of the fuselage.
2. GNSS antennas must be installed to provide the widest, unobstructed view of GNSS
satellites.
2-18
Attenuation Min Length (ft)
(dB/100 ft @ 1 GHz)
27.1
25.8
14.5
12.8
7.5
Max Length
(ft)
5.5 18.5
5.8 19.4
10.3 34.5
11.7 39.1
20 66.7
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