CONNECTI V IT Y
now in use, we have proved we
can bring together all the elements
required – in space, on the ground and in between
– to change the face of connectivity.”
SATELLITE CHANGES
Viasat contends that GEO satellites are a more efficient
solution; saying that many LEO satellites are required to
do the job of one GEO satellite, and that GEO reaches the
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APRIL 2020 023
circumference of others, so they can scoop
up twice the bandwidth,” says Cordone.
“The size and shape also means coverage
around the world is better. However, the
antenna is also very thin and maintains
a low profile above the fuselage, reducing
drag and fuel burn. It also has few moving
parts, increasing reliability.”
DIFFERENT ORBIT
While Cordone advocates the Ku and dual
antennae approach, others are looking
at other technologies. Newcomer
OneWeb plans to use Ka- and Ku-
bands in conjunction with a
constellation of 650 LEO
satellites covering the whole
planet. The plan is to go live in
2021, offering an average
latency of 32ms and speeds
of more than 400Mbps. The
company has already proved it can
support live streaming of video and
HD TV from space.
“Spectrum is a scarce resource,” says
Ruth Pritchard-Kelly, vice president of
regulatory matters for OneWeb. “The
reality is that no matter how good your
network is, success is not possible without
the right spectrum. With our spectrum
Completion
centres are noting an
increase in aircraft fitted
with two different types
of connectivity, for
redundancy – a topic
to be explored in
the July 2020 issue
KA-, KU- AND L-BAND
Inflight connectivity depends on satellite
communication between aircraft and the
ground-based internet. Satellites are the only
viable way of connecting aircraft as, due to
their relatively high altitude, they cover large
areas of the sky – meaning the aircraft can
stay connected to the same satellite for long
periods of its journey.
However, there are several different ways
in which such satcoms work. Primarily this
revolves around the frequency bands used
to transmit between the satellite and aircraft
and vice versa – which is a lot more crucial
than you may think.
Typically, these transmissions use Ka, Ku
or L frequency ranges. L-band uses
frequencies in the 1-2GHz range; Ku-band
utilises approximately 12-18GHz; and Kaband
services use the 26.5-40GHz segment
of the electromagnetic spectrum. ‘Ku’ stands
for ‘Kurz-unten’ – German for the band just
underneath the ‘short’ or ‘K’-band. Perhaps
unsurprisingly, ‘Ka’ stands for ‘Kurz above’.
This is because Ku is the lower part
of the original NATO K band, which was split
into three bands (Ku, K and Ka) because of
the presence of the atmospheric water
vapour resonance peak at 22.24 GHz
(1.35cm), which made the centre unusable
for long-range transmission.
The choice of spectrum is important
because the frequency determines how much
data can be transmitted. According to the
Shannon Theorum – calculated by physicist
and mathematician Claude Shannon in 1948 –
the higher the bandwidth, the more data can
be transferred, while the higher the frequency
the more bandwidth is available.
places that actually need to be connected.
The company is launching a new
constellation to boost capacity without
existing customers having to upgrade
hardware. “Whereas in the past, a satellite
with 10GBps of capacity might have been
seen as high capacity, our smallest Ka-band
satellite – ViaSat One – has 140GBps,” says
Person. “ViaSat Two is 260Gbps and our
next generation will offer 1TBps each.
Having that much capacity allows us to
provide a very consistent service.”
Inmarsat says that its network of GEO
satellites enables it to deliver consistency to
Jet Connex Ka-band users. GEO satellites
ABOVE AND RIGHT:
INMARSAT’S JET CONNEX
BROADBAND IS DELIVERED
THROUGH GEO SATELLITES
BELOW: INMARSAT BOOSTED
ITS SERVICE BY LAUNCHING
A FIFTH SATELLITE IN
NOVEMBER 2019
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