Avionics News June 2022 - 26

IT TAKES TWO TO TANGO ON 5G
Continued from page 24
who is president of FreeFlight Systems of Irving, Texas. Rios
has two decades of experience with aviation technology startup
companies and is a computer engineer and a general aviation
pilot with a commercial rating.
The solution has to be in the LRU, not just with the antenna.
Just inserting a filter between the antenna and the LRU will
require redesign of legacy radar altimeters, which he thinks
might take 18 months to be TSO'ed, and that is a long time.
In 2019, FreeFlight started to design a new model of radar
altimeter at a time when it looked like telecom companies
might start transmitting at a higher power setting for 5G on
nearby frequencies. The company modeled 5G and how to
counter interference into the new design to avoid that problem
as much as possible.
The result was a new model, the
RA 4500 Mark 2, which is a drop-in
replacement with the same form, fit
and function for the previous model
RA 4500 introduced 15 years ago.
FreeFlight also developed the Terrain
Series RA 5500 and RA 6500 for
use in Part 135 regional jet, business,
general aviation, military, rotorcraft
and unmanned aircraft. The company
said the RA 5500 is designed for
single installation, and the RA 6500 is
designed for dual installation. Both are
configured with digital signal processing to
resist 5G interference.
Rios said a lot of regional jets, Part 29 helicopters and most
development and verification to address the market for Level A
Part 121 narrow and wide-body airline aircraft. Rios noted the
approvals for operations in areas with 5G towers near airports is
only temporary.
All radar altimeters are susceptible to 5G interference,
whether it is 10 miles from a 5G tower or 1 mile. FreeFlight's
new radar altimeters are good to within 0.1 mile of a 5G
transmitter, and the FAA asked Verizon and AT&T not to
allow 5G transmitters closer than a mile from the runway
environment. " As of right now, our radar altimeter is not
perfect, but our digital platform will continue to improve over
time; 0.1 mile is good but not good enough. If you fly over a
5G tower, 0.1 mile is 500 feet vertically, " Rios said.
In Phoenix, Arizona, Honeywell takes the issue of possible
5G interference with its radar altimeters as a serious matter
and is working with the FAA and aircraft manufacturers to
test its systems for 5G interference. Its radar
altimeters meet all existing FAA and
manufacturer certification requirements.
If anything changes, the company said it
will verify that its systems are compatible.
In Scottsdale, Arizona, VIAVI Solutions
provides test equipment that can help
radar altimeter manufacturers and
airline maintenance, repair and overhaul
operations to check whether their equipment is
susceptible to 5G interference. The company has
FreeFlight's RA 5500
been making the ALT-8000 for 10 years, which can
test 90% of commercial radar altimeters and
has a new testbed, the ALT-9000, which can
test all radar altimeters on the market. This
heavier business jets require dual systems. Regional jet and
EMS helicopter operators are showing a lot of interest in the
RA 6500. In addition, the RA 5500's weight of just 1.9 pounds
and its 3.06-by-6.78-by-3.15-inch compact size has attracted
the attention of unmanned aircraft companies. The Terrain
Series units will be TSO certified by June and can be integrated
with RAD-45 and other display indicators for accurate LED
readings of AGL altitudes up to 2,500 feet. Terrain Series units
can be retrofitted in legacy aircraft with existing antennas,
control heads and cabling. An NVG display is also available.
FreeFlight's new radar altimeters are about to receive a TSO
so shipments can begin before June.
Rios said the RA 4500 is currently installed on a lot of light
helicopters such as Robinson, Bell, Airbus, and light airplanes,
including Grob, Diamond, and Daher TBM where the drop-in
replacement of the RA 4500 Mark 2 is drawing a lot of interest.
FreeFlight has sold 5,000 of its legacy radar altimeters.
In the future, the company is eying additional software
26 avionics news * june 2022
includes ones with low probability of intercept, combined radar
altimeter and next-generation variants.
The ALT-9000 can be used with VIAVI's testbed group
of products to be externally exercised with VIAVI's Ranger,
which can inject custom-created RF signals or broadband
recording of 5G signals into a test sequence. Then VIAVI's
OneAdvisor 800 can conduct real-time spectrum analysis with
2D and 3D spectrogram plots.
" At VIAVI, we have a unique current understanding
about the potential interference in C-band, as we are deeply
involved in both 5G communications and radar altimeter
technologies, " said Sameh Yamany, VIAVI's chief technology
officer. This will help industry and government regulators
tackle issues comprehensively to enable telecoms and
aviation to operate in harmony.
VIAVI is getting a lot of interest in the ALT-9000 from the
U.S. military, including Navy and Army test centers. " Right
now, we are just trying to help all of our customers understand
any interference issues that may exist with 5G, " said Terry
Jarboe, ALT-9000 business development manager. q
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