L A SER C ONNECTI V IT Y
THE TECHNICAL CHALLENGES
Because laser systems require a clear line of sight between the
aircraft and the geostationary satellite, new antenna hardware
must be designed that will produce the minimum amount of
drag when installed on top of the aircraft’s fuselage.
“We are trying to develop a special optical array antenna
using a flat structure with small lenses that is able to receive
optical signals and track them also, because your aircraft is
moving,” says Dr Hauschildt. “You have to track the antenna or
you have to track the beam of the antenna to receive and transmit
data, and this is something that we are working on in the ScyLight
program right now. The laser’s optical signal can be sent through a
telescope, which can be pointed anywhere you want. It can be done in
orbit between satellites, or between satellites and the ground, and there
are also ongoing experiments between ground and aircraft directly”.
A partner in this process is Tesat-Spacecom, the technical lead for
developing and manufacturing the optical terminals: “For RF, you need
big antennas, but when using optics we have a big advantage in that the
narrow laser beam only needs a small telescope – ours is 135mm (5.3in)
– it’s a very small technology,” says Matthias Motzigemba, head of sales
communication systems at Tesat-Spacecom GmbH.
Another challenge is that laser signals can be affected by poor
weather. But that’s where the EDRS comes into play. There are two laserequipped
GEO satellites already deployed covering Europe and North
Africa, but eventually there will be four, to cover the Atlantic and the
Pacific regions too. By using the
linkage between the GEO and
LEO satellites and the ground
stations, low-visibility weather
can be circumvented by uploading
and downloading signals from a
ground station to a satellite link
073
“ When using optics the
laser beam only needs
a small telescope”
LOW-EARTH ORBIT TESTS SUCCESSFUL
aircraftinteriorsinternational.com
SEPTEMBER 2019
No red tape...yet
Today’s in-flight data connectivity
environment is heavily regulated
and the Ku and Ka bandwidth
used for today’s onboard wi-fi has
capacity limitations.
“Nowadays you have to go
through a frequency authorisation
process to get permission to use
it, and another requirement – for
transfer of high data rates – is
that you need high bandwidth,
so you need RF (radio frequency)
spectrum to transfer high data
rates” says Matthias Motzigemba,
head of sales for communication
systems at Tesat-Spacecom
GmbH, the company taking
the technical lead for ESA’s
fibre-in-the-sky.
“All these problems will
disappear when you are using
optics. So lasercom or optical
communication using laser
is not regulated in terms of
frequency, so you do not have
to ask for harmonisation,
you can just use it, and
optical communication
has nearly unlimited
spectrum in
terms of data
rates.”
In other inflight connectivity developments,
on 2 July ThinKom Solutions announced
the completion of the first live test
of a commercially available phasedarray
antenna with Telesat’s Phase 1
LEO satellite. The test was performed
using a ThinKom Ka2517 aeronautical
satcom antenna which, according to the
company, successfully acquired, tracked
and maintained seamless end-to-end
connectivity with the Telesat LEO satellite.
Full-duplex throughput data rates of
up to 370Mbps on the downlink and
110Mbps on the uplink were achieved
at “extremely high” spectral efficiencies,
while demonstrating the ultra-low latency
capabilities (20-40msec) of the LEO
satellite. The antenna was also reported
to have reliably transitioned from tracking
the LEO satellite to a geostationary (GEO)
satellite and back to the LEO satellite, with
switching times consistently under one
second and elevation angles as low as 10°
above the horizon.
“These on-air tests confirm that our
phased-array antenna architecture
provides the beam agility, switching
speeds, low look-angles and high spectral
efficiencies required to communicate over
a LEO network,” said Bill Milroy, ThinKom’s
chairman and CTO. “We are moving
into the next phase of development and
commercialisation of an Enterprise User
Terminal for Telesat’s LEO system.”
Milroy also states that ThinKom has
conducted successful on-air demos
with the Ka2517 across multiple GEO
satellites and medium-earth orbit (MEO)
constellations from fixed platforms, as well
as an aircraft in flight.
which uses a much narrower beam than
existing radio frequency systems of data
transfer – means that the links avoid
interference and detection. This will make
the links virtually unhackable, which
should alleviate anxieties in an age of data
privacy and security concerns when it
comes to airborne executives sharing
sensitive corporate information with their
offices, or exchanges of personal payment
data when making onboard purchases.
BELOW: THINKOM’S KA2517
SATCOM ANTENNA MAINTAINED
CONNECTIVITY WITH THE TELESAT
LEO SATELLITE
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