Antenna Power; Recommended Cable; Satcom Compatibility; Tc978 Static Pressure Connection - FreeFlight ADS-B FDL-978 Series Installation Manual

3. Antenna placement on the airframe should be optimized to ensure the sensor can take
full advantage of a 5 degree mask angle. This includes consideration of antenna location
with respect to blockage from all aircraft components at typical level cruising attitude, as
well as minimizing the effects of aircraft shadowing during typical maneuvers.
4. The antenna should be separated as much as practical from transmitting antennas. For
small aircraft, the antenna should also be separated as much as practical from the
windscreen to prevent case-to-antenna coupling.
5. For installations on rotorcraft, the effects of the rotor blades on antenna performance
should be considered. This may require additional equipment functional flight evaluation
or analytical evaluation to confirm the suitability of antenna location.
6. For multiple-sensor installations, the installer should reduce the likelihood that a single
lightning strike affects all the sensors.
2.11.1

Antenna Power

The internal GPS of the FDL-978 Series and FDL-978 Lite Series utilizes an active antenna
which means the antenna includes a low noise amplifier. The power for the low noise amplifier
is provided from the GPS receiver via the antenna coax cable. No other installation
considerations are necessary.
2.11.2

Recommended Cable

RG-400 or RG-142 cable with a maximum length of 50 ft is recommended. The cable, including
connectors, loss should not exceed 10dB.
For antennas mentioned in Section 1.7.1, RG-400 or RG-142 cable with a maximum length of
25 ft is recommended. The cable including connectors, loss should not exceed 5dB.
2.11.3

SATCOM Compatibility

The FDL-978 Series and FDL-978 Lite Series internal GPS/WAAS Sensor has been shown via
testing to be specification compliant for single-channel SATCOM compatibility per RTCA/DO-
229D.
Extra care should be exercised when installing GNSS equipment on aircraft with SATCOM
having multiple channels, as cautioned in Sec. 14-1 of AC 20-138B. " GNSS equipment is
particularly susceptible to out-of-band SATCOM emissions and in-band inter-modulation
between multiple channel SATCOM installations. GNSS equipment must not be installed in
aircraft with multiple SATCOM channels unless the simultaneous use of interfering
frequencies can either be prevented or demonstrated not to interfere with the operation of
the GNSS equipment."

2.12 TC978 Static Pressure Connection

The TC978 Controller includes an altitude encoder which must be connected to the same
source of static pressure as the primary altimeter on the aircraft if this sensor is utilized in the
installation. The TC978 static pressure port provides a mounting spigot intended for nominal 5
mm or 3/16 in inside diameter tubing. A length of EPDM rubber tubing is included in the
installation kit to facilitate connection to the aircraft static system.
FFS Copyright © 2015 All rights reserved.
ADS-B FDL-978 Series and
Lite Series Installation Manual
Document No. 87343 Rev F
2-19