Home' Position : Position 86 Dec-Jan 2017 Contents Full operational status for the
five independent satellite-based
navigation systems—the sub-
components of the System of Positioning
Systems—is still at least a decade away.
I could have, indeed I did, write the
same thing a decade ago. The difference is
that a decade ago there was considerable
debate within all the networks on the
shape of a future GNSS; who would fund
it; how would frequencies be allocated;
and how many satellites would each
system contain. Today, the shape of the
future is clear. The money is allocated.
Three of the systems are already fully
operational. All of the others have some,
if not all, of their operational satellites in
place. Most of the inter-system wrangling
over frequencies and interference is over.
In fact, we are living through a golden
age in GNSS. The size of the combined
investment around the world is colossal.
Some 14 positioning satellites were
launched in 2015.
The roots of position determination
using radio waves go back to the dark
days of World War II, when the British
developed the Decca Navigator for the
Royal Navy. It was an electronic receiver
that triangulated signals from shore
stations. In the 1960s, the US military
used the same idea, but satellites replaced
the shore stations. It could provide a
fix once an hour using electronics that
could be shoehorned into the back of a
Hercules aircraft. They called it Transit. It
was the precursor to GPS and marked the
launch of an international space race still
The first real GPS
satellites were launched
between 1978 and 1985
by the United States
Department of Defense. At the time they
were called Navstars, but the ten satellites
in the system are now usually referred to
as GPS Block I. The first modern Block
IIA bird was launched in 1989. The GPS
achieved full operational capacity in
1993, when 24 satellites were in orbit.
None of these satellites are still
operational, although many of them are
still in parking orbit and could be turned
on again if required.
The oldest operational satellites
now on orbit are the 12 Block IIR GPS
satellites launched between 1997 and
2004. Eight Block IIR-M satellites were
launched between 2005 and 2009 followed
by 12 Block IIF between 2010 and 2016.
The first of the new Block IIIA satellites
will fly in 2017 and will be roughly
contemporaneous with Japan's Quazi
Zenith Satellite System.
The first of Japan’s
satellites, QZSS-1 or
Michibiki, was launched
in 2010. Mitsubishi
Electric is currently building another three
ahead of a launch date in 2017. While this
system will be under Japanese national
control, its four satellites will produce
GPS-like signals and so will work with GPS
receivers. The constellation is designed so
that one QZSS satellite will always be close
to the zenith over Japan, giving improved
reception in urban canyons where
conventional GPS is severely compromised.
Because of the nature of the orbits,
signals from the QZSS satellites will also
be available in parts of South East Asia
and Australia. Studies by the Cooperative
Research Centre for Spatial Information
were able to show that QZSS signals could
provide 5cm positioning across regional
Australia without CORS.
The Europeans began
serious work in 1999,
when the initial system
design for the Galileo
system was finalised. The first test satellite,
Giove-A, was launched in 2005.
The complete constellation of 30
satellites is now scheduled for 2020. It
seems a long time, but the Europeans
have been about as fast and effective
as the US in developing their system.
Moreover, the Europeans have had to
overcome problems inherent in building
a single system to satisfy all the member
countries of the European Union as well
as enormous uncertainty around the
Galileo will broadcast a basic service
and provide a high-precision service to
fee-paying customers. It will provide a
global search and rescue service that
will replace the current Cospas-Sarsat
system. It also has a Safety of Life
navigation feature, which provides
integrity information to the receiver to
warn of errors.
A contract was let in 2010 to Surrey
Satellite Technology in the UK and
OHB Systems in Germany for the first
14 operational satellites. In 2012, OHB
received a second contract for a further
eight satellites. All 14 had been launched
by May 2016. Four more were launched in
November to join the constellation.
The Galileo program has, at certain
times, allowed nations outside the EU
to take financial positions in the system.
The Chinese were initially very excited by
the possibilities afforded by the project
and in 2003 committed 230 million
Euros to it. By April 2006, agreements
on eleven projects had been signed
between China and the EU. However, the
South China Morning Post reported in
A survey of the state of Global Navigation Satellite Systems
Photograph of Earth
and moon taken aboard
the International Space
Station at an orbit of
approximately 400 km. By
comparison, GPS satellites,
such as that shown here,
orbit at an altitude of
approximately 20,200 km.
32 position December/January 2017
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